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Brightened Optical Transition Hinting to Strong Spin-lattice Coupling in a Layered Antiferromagnet

Advanced Science 2408343 (2025)

Materials known as multiferroics exhibit more than one primary ferroic order in a given phase. The coexistence of multiple physical phases is highly interesting because through coupling of these orders...

Structural Modulation and Enhanced Magnetic Ordering in Incommensurate K1–xCrSe2 Crystals

J. Am. Chem. Soc. 2025

Layered delafossite-type compounds and related transition metal dichalcogenides, characterized by their triangular net structures, serve as prototypical systems for exploring the intricate interplay between...

Efficient soft-chemical synthesis of large van-der-Waals crystals of the room-temperature ferromagnet 1T-CrTe2

J. Mater. Chem. A, 2025, Advance Article

We herein report on a fast and convenient soft-chemical synthesis approach towards large 1T-CrTe2 van-der-Waals crystals. This compound is formed X-ray diffraction pure, with a complete conversion...

Universal Scaling near Band-Tuned Metal-Insulator Phase Transitions

Phys. Rev. Lett. 131, 196303 (2023)

We present a theory for band-tuned metal-insulator transitions based on the Kubo formalism. Such a transition exhibits scaling of the resistivity curves in the regime...

Electron-Beam Writing of Atomic-Scale Reconstructions at Oxide Interfaces

Accepted in Nanoletters

The epitaxial growth of complex oxides enables the production of high-quality films, yet substrate choice is restricted to certain symmetry and lattice parameters, thereby limiting the technological...

Role of the coupling of the electronic transitions on the order of the metal-to-insulator phase transition in nickelates

APL Mater. 12, 081120 (2024)

Rare-earth nickelates (chemical formula RNiO3, R being a rare-earth cation) display a temperature-dependent metal-to-insulator transition (MIT) together with a breathing distortion of the...

Interplay between Point and Extended Defects and Their Effects on Jerky Domain-Wall Motion in Ferroelectric Thin Films

Phys. Rev. Lett. 133, 106801 (2024)

Defects have a significant influence on the polarization and electromechanical properties of ferroelectric materials. Statistically, they can be seen as random pinning centers acting on an elastic manifold,...

Controlling the Magnetic Properties of the van der Waals Multiferroic Crystals Co1–xNixI2

Chem. Mater. 2024

The structurally related compounds NiI2 and CoI2 are multiferroic van der Waals materials in which helimagnetic orders exist simultaneously with electric polarization. Here, we report on ...

Mapping orthorhombic domains with geometrical phase analysis in rare-earth nickelate heterostructures

Mundet et al. – APL Mater. 12, 031124 (2024)

Most perovskite oxides belong to the Pbnm space group, composed of an anisotropic unit cell, A-site antipolar displacements, and oxygen octahedral tilts. Mapping the orientation of the orthorhombic unit cell...

Structural study of nickelate based heterostructures

Varbaro et al. – APL Mater. 12, 031104 (2024)

Heterostructures consisting of SmNiO3 and NdNiO3 alternating layers with additional LaAlO3 spacer layers were grown and fully characterized by means of x-ray diffraction,...

Chemical Principles of Intrinsic Topological Superconductors

Chem. Mater. 2023

The concept of topological superconductivity has attracted immense interest in the physics community recently for several reasons: First, topological superconductors represent new phases of matter, which are...

Observation of the orbital inverse Rashba–Edelstein effect

El Hamdi  et al. – Nat. Phys. (2023).

The spin–orbit interaction plays an important role in magnetism and in many quantum materials. It is the cornerstone of the physics of many electronic phases that emerge at interfaces because of broken...

Multiple antiferromagnetic phases and magnetic anisotropy in exfoliated CrBr3 multilayers

Nature Communications volume 14, 4969 (2023)

In twisted two-dimensional (2D) magnets, the stacking dependence of the magnetic exchange interaction can lead to regions of ferromagnetic and antiferromagnetic interlayer order, separated by non-collinear,...

Determining spin-orbit coupling in graphene by quasiparticle interference imaging

Nature Communications 14 1, 3771 (2023)

We deploy quasi-particle interference imaging using a scanning tunneling microscope to probe the presence, nature and strength of proximity induced spin-orbit coupling (SOC) in single layer graphene (SLG) on...

Coupling of magnetic phases at nickelate interfaces

Domínguez et al. – Physical Review Materials 7, 065002 (2023)

In this paper we present a model system built out of artificially layered materials, allowing us to understand the interrelation of magnetic phases with the metallic-insulating phase at long length scales,...

Mapping the complex evolution of ferroelastic/ferroelectric domain patterns in epitaxially strained PbTiO3 heterostructures

Lichtensteiger et al. – APL Mater 11, 061126 (2023)

We study the complex ferroelastic/ferroelectric domain structure in the prototypical ferroelectric PbTiO3 epitaxially strained on (110)o-oriented DyScO3 substrates, using a...

Synthesis and anisotropic magnetic properties of LiCrTe2 single crystals with a triangular-lattice antiferromagnetic structure

J. Phys. Mater. 6 035001. 2023

We report on the synthesis of LiCrTe2 single crystals and on their anisotropic magnetic properties. We have obtained these single crystals by employing a Te/Li-flux synthesis method. We find...

Gate-Controlled Magnetotransport and Electrostatic Modulation of Magnetism in 2D Magnetic Semiconductor CrPS4

Advanced Materials volume 35, 2211653 (2023)

Using field-effect transistors (FETs) to explore atomically thin magnetic semiconductors with transport measurements is difficult, because the very narrow bands of most 2D magnetic semiconductors cause...

Electronic Coupling of Metal-to-Insulator Transitions in Nickelate-Based Heterostructures

Varbaro et al. – Adv. Electron.Mater.2023, 2201291

In rare earth nickelates, the metal-to-insulator transition observed as a function of temperature can be described using an electronic and a structural order parameter. The electronic one is linked to the...

Oxygen isotope effect in VO2

Rischau et al. – Phys. Rev. B 107, 115139

We investigate the oxygen isotope effect on the VO2 metal-insulator transition. Using an alternative method, we synthesize V16O2 and V18O2 crystals,...

Competition between Carrier Injection and Structural Distortions in Electron-Doped Perovskite Nickelate Thin Films

Hadjimichael et al. – Adv. Electron.Mater.2023, 2201182

The discovery of superconductivity in doped infinite-layer nickelate thin films has brought increased attention to the behavior of the doped perovskite phase. Despite this interest, the majority of existing...

Full Control of Solid‐State Electrolytes for Electrostatic Gating

Advanced Materials, 2211993 (2023)

Ionic gating is a powerful technique to realize field-effect transistors (FETs) enabling experiments not possible otherwise. So far, ionic gating has relied on the use of top electrolyte gates, which pose...

Structural and electronic properties of SrCuO2+δ thin films

APL Materials 10, 101112 (2022)

The layered structure of superconducting cuprates is considered to be a key ingredient to achieve high superconducting transition temperatures. In this work, we investigate the possibility of doping the...

Dynamic magnetic crossover at the origin of the hidden-order in van der Waals antiferromagnet CrSBr

Nature Communications volume 13, 4745 (2022)

The van-der-Waals material CrSBr stands out as a promising two-dimensional magnet. Here, we report on its detailed magnetic and structural characteristics. We evidence that it undergoes a transition to an...

Quenching the bandgap of two-dimensional semiconductors with a perpendicular electric field

Nature Nanotechnology volume 17, 1078 (2022)

Perpendicular electric fields can tune the electronic band structure of atomically thin semiconductors. In bilayer graphene, which is an intrinsic zero-gap semiconductor, a perpendicular electric field opens...

Heating-Induced Performance Degradation of REBa2Cu3O7–x Coated Conductors: An Oxygen Out-Diffusion Scenario with Two Activation Energies

ACS Appl. Electron. Mater. 2022, 4, 3, 1318–1326

The degradation of the superconducting properties of REBa2Cu3O7–x coated conductors when heated above 150 °C is a topic of concern for any...

Light sources with bias tunable spectrum based on van der Waals interface transistors

Nature Communications volume 13, 3917 (2022)

Light-emitting electronic devices are ubiquitous in key areas of current technology, such as data communications, solid-state lighting, displays, and optical interconnects. Controlling the spectrum of the...

Resonant Inelastic X-Ray Scattering Study of Electron-Exciton Coupling in High-T c Cuprates

Physical Review X 12, 021062 (2022)

Explaining the mechanism of superconductivity in the high-T c cuprates requires an understanding of what causes electrons to form Cooper pairs. Pairing can be mediated by phonons, the screened Coulomb force,...

Crystal growth and structure of a high temperature polymorph of Sr2TiO4 with tetrahedral Ti-coordination, and transition to the Ruddlesden–Popper tetragonal phase

CrystEngComm, 2022,24, 3731-3740

Single crystals of transition metal oxides forming the Ruddlesden–Popper series are necessary for complete studies of their often exciting physical properties. In the strontium titanate family, crystal...

Quasi 1D Electronic Transport in a 2D Magnetic Semiconductor

Advanced Materials (2022)

We investigate electronic transport through exfoliated multilayers of CrSBr, a 2D semiconductor that is attracting attention because of its magnetic properties. We find an extremely pronounced anisotropy...

A Heavy Fermion Zn-Deficient CaBe2Ge2-Type Phase with Rare Ce-Based Ferromagnetism and Large Magnetoresistance

Chem. Mater. 2022 vol. 34, no. 5, p. 2352-2360

We report on the hitherto unknown compound CeZn2−δGe2 (δ ≈ 0.41). We find that this compound crystallizes in a defect version of the well-known CaBe2Ge2...

Generation of Tunable Stochastic Sequences Using the Insulator–Metal Transition

Nano Lett. 2022, 22, 3, 1251–1256
Probabilistic computing is a paradigm in which data are not represented by stable bits, but rather by the probability of a metastable bit to be in a particular state. The development of this technology has...

Magnetization dependent tunneling conductance of ferromagnetic barriers

Nature Communications volume 12, 6659 (2021)

Recent experiments on van der Waals antiferromagnets have shown that measuring the temperature (T) and magnetic field (H) dependence of the conductance allows their magnetic phase diagram to be mapped....

Group-9 Transition-Metal Suboxides Adopting the Filled-Ti2Ni Structure: A Class of Superconductors Exhibiting Exceptionally High Upper Critical Fields

Chem. Mater. 2021, 33, 22, 8722–8732

Ti2Ni and the related η-carbide structure are known to exhibit various intriguing physical properties. The Ti2Ni structure with the cubic space group Fd3̅m is surprisingly complex,...

Multiband charge density wave exposed in a transition metal dichalcogenide

Nature Communications 12, 6037 (2021)

In the presence of multiple bands, well-known electronic instabilities may acquire new complexity. While multiband superconductivity is the subject of extensive studies, the possibility of multiband charge...

Theory of cross quantum capacitance

Phys. Rev. Research 3, 043036 – 14 October 2021
Impressive progress in the control of atomically thin crystals is now enabling the realization of gated structures in which two electrodes are separated by atomic scale distances. The electrical capacitance...

Synthetic control over polymorph formation in the d-band semiconductor system FeS2

Chem. Sci., 2021, 12, 13870

Pyrite, also known as fool's gold is the thermodynamic stable polymorph of FeS2. It is widely considered as a promising d-band semiconductor for various applications due to its intriguing physical...

Observation of flat bands in twisted bilayer graphene

Nature Physics 17, 189 (2021)

Using angle-resolved photo-emission spectroscopy we are the first to report a direct observation of the flat bands in twisted bilayer graphene. I calculated the matrix elements that determine how the flat...

Coupling Charge and Topological Reconstructions at Polar Oxide Interfaces

Phys. Rev. Lett. 127, 127202 (2021)

In oxide heterostructures, different materials are integrated into a single artificial crystal, resulting in a breaking of inversion symmetry across the heterointerfaces. A notable example is the interface...

Two-gap to single-gap superconducting transition on a honeycomb lattice in Ca1−xSrxAlSi

Phys. Rev. Research 3, 033192, 2021

We report on the structural and microscopic superconducting properties of the Ca1−xSrxAlSi solid solution. Specifically, we have realized the continuous solid solution, which for all members, other than x=0 ...

Wang-MacDonald d-wave vortex cores observed in heavily overdoped Bi2Sr2CaCu2O8+δ

Phys. Rev. X 11, 031040 (2021)

The electronic structure of the vortex cores in copper oxide high temperature superconductors (HTS) is a long-standing puzzle. Using scanning tunneling spectroscopy at an unprecedented low magnetic field for...

Coherent spin-wave transport in an antiferromagnet

Nature Physics volume 17, pages 1001–1006 (2021)

Magnonics is a research field complementary to spintronics, in which the quanta of spin waves (magnons) replace electrons as information carriers, promising lower dissipation. The development of ultrafast,...

Superconductivity with High Upper Critical Field in the Cubic Centrosymmetric η-Carbide Nb4Rh2C1−δ

ACS Mater. Au 2021, 1, 1, 55–61

The upper critical field is a fundamental measure of the strength of superconductivity in a material. It is also a cornerstone for the realization of superconducting magnet applications. The critical field...

Hofstadter subband ferromagnetism and symmetry broken Chern insulators in twisted bilayer graphene

Nature Physics 17, 478 (2021)

Transport measurements of twisted bilayer graphene reveal a sequence of spin and valley polarized states with Chern numbers 1, 2, 3. We can understand these states using a Hartree theory on top of a...

Controlling the anisotropy of a van der Waals antiferromagnet with light

Science advances. 2021, vol. 7, no. 23

Van der Waals magnets provide an ideal playground to explore the fundamentals of low-dimensional magnetism and open opportunities for ultrathin spin-processing devices. The Mermin-Wagner theorem dictates that ...

Nanoinfrared Characterization of Bilayer Graphene Conductivity under Dual-Gate Tuning

Nano Lett. 2021, 21, 12, 5151–5157

Dual-gate tuning on two-dimensional (2D) heterostructures can provide independent control of the carrier concentration and interlayer electrostatic potential, yielding novel electronic and optical properties. ...

Designing and controlling the properties of transition metal oxide quantum materials

Nature Materials volume 20, pages 1462–1468 (2021)

This Perspective addresses the design, creation, characterization and control of synthetic quantum materials with strong electronic correlations. We show how emerging synergies between...

Roughness and dynamics of proliferating cell fronts as a probe of cell–cell interactions

Scientific Reports volume 11, 8869 (2021)

Juxtacellular interactions play an essential but still not fully understood role in both normal tissue development and tumour invasion. Using proliferating cell fronts as a model system, we explore the...

Machine learning applied to X-ray tomography as a new tool to analyze the voids in RRP Nb3Sn wires

Scientific Reports, 11, 7767 (2021)

The electro-mechanical and electro-thermal properties of high-performance Restacked-Rod-Process (RRP) Nb3Sn wires are key factors in the realization of compact magnets above 15 T for the future...

Local Probe Comparison of Ferroelectric Switching Event Statistics in the Creep and Depinning Regimes in Pb(Zr0.2Ti0.8)O3 Thin Films

Phys. Rev. Lett. 126, 117601

Ferroelectric materials provide a useful model system to explore the jerky, highly nonlinear dynamics of elastic interfaces in disordered media. The distribution of nanoscale switching event sizes is studied...

Very high upper critical fields and enhanced critical current densities in Nb3Sn superconductors based on Nb–Ta–Zr alloys and internal oxidation

Journal of Physics: Materials, Volume 4, Number 2, 2021

The inhibition of Nb3Sn grain growth in the presence of ZrO2 nanoparticles appears to be one of the most promising method for pushing the critical current densities of Nb3Sn...

Near-Atomic-Scale Mapping of Electronic Phases in Rare Earth Nickelate Superlattices

Nano Lett. 2021, 21, 6, 2436–2443

Nanoscale mapping of the distinct electronic phases characterizing the metal–insulator transition displayed by most of the rare-earth nickelate compounds is fundamental for discovering the true nature of...

Polytypism and superconductivity in the NbS2 system

Dalton Trans., 2021,50, 3216-3223

We report on the phase formation and the superconducting properties in the NbS2 system. Specifically, we have performed a series of standardized solid-state syntheses in this system, which allow us ...

HTS Accelerator Magnet and Conductor Development in Europe

Instruments 2021, 5(1), 8

In view of the preparation for a post-LHC collider, in 2010 the high-energy physics (HEP) community started to discuss various options, including the use of HTS for very high-field dipoles. Therefore, a small ...

Ultrafast control of magnetic interactions via light-driven phonons

Nature Materials volume 20, pages 607–611 (2021)

Resonant ultrafast excitation of infrared-active phonons is a powerful technique with which to control the electronic properties of materials that leads to remarkable phenomena such as the light-induced...

Phase coherence in out-of-equilibrium supersolid states of ultracold dipolar atoms

Nature Physics volume 17, pp. 356–361 (2021)

A supersolid is a counterintuitive phase of matter that combines the global phase coherence of a superfluid with a crystal-like self-modulation in space. Recently, such states have been experimentally...

Insight into the Charge Density Wave Gap from Contrast Inversion in Topographic STM Images

Phys. Rev. Lett. 125, 267603 (2020)

We present a first detailed study of the charge density wave (CDW) contrast inversion in scanning tunneling microscopy (STM) images. Combining high resolution STM imaging at different tunneling biases and...

High-field superconductivity in C-doped MgB2 bulk samples prepared by a rapid synthesis route

Scientific Reports, 10, 17656 (2020)

The upper critical field sets the thermodynamic limit to superconductivity. A big gap is present between the upper-critical-field values measured in MgB2 polycrystalline bulk superconductors and...

Observation of flat bands in twisted bilayer graphene

Nature Physics (2021)

We combine different imaging techniques and angle-resolved photoemission with simultaneous real- and momentum-space resolution (nano-ARPES) to directly map the band dispersion in twisted bilayer graphene...

Flipping exciton angular momentum with chiral phonons in MoSe2/WSe2 heterobilayers

2D Materials 2020, vol. 7, no. 041002

Optical selection rules in monolayers of transition metal dichalcogenides and of their heterostructures are determined by the conservation of the z-component of the total angular momentum—JZ =...

Length scales of interfacial coupling between metal and insulator phases in oxides

Nature Materials volume 19, pages 1182–1187 (2020)

Controlling phase transitions in transition metal oxides remains a central feature of both technological and fundamental scientific relevance. A well-known example is the metal–insulator transition, which...

Vibrational properties of LaNiO3 films in the ultrathin regime

APL Materials 8, 061102 (2020)

Collective rotations and tilts of oxygen polyhedra play a crucial role in the physical properties of complex oxides such as magnetism and conductivity. Such rotations can be tuned by preparing thin films in...

Giant anomalous Hall effect in quasi-two-dimensional layered antiferromagnet Co1/3NbS2

Physical Review Research. 2020, vol. 2, no. 2, 023051

The discovery of the anomalous Hall effect (AHE) in bulk metallic antiferromagnets (AFMs) motivates the search of the same phenomenon in two-dimensional (2D) systems, where a quantized anomalous Hall...

Dipolar interactions between localized interlayer excitons in van der Waals heterostructures

Nature Materials volume 19, pages 624–629 (2020)

Although photons in free space barely interact, matter can mediate interactions between them resulting in optical nonlinearities. Such interactions at the single-quantum level result in an on-site photon...

Multi-frequency Shubnikov-de Haas oscillations in topological semimetal Pt2HgSe3

2D Materials. 2020, vol. 7, no. 025042

Monolayer jacutingaite (Pt2HgSe3) has been recently identified as a candidate quantum spin Hall system with a 0.5 eV band gap, but no transport measurements have been performed so far...

Electronic structure of the dual-topology semimetal Pt2HgSe3

Phys. Rev. Lett. 124, 106402 (2020)

We report high-resolution angle-resolved photoemission measurements on single crystals of Pt2HgSe3 grown by high-pressure synthesis. Our data reveal a gapped Dirac nodal line whose (001) projection separates...

Determination of the electromechanical limits of high-performance Nb3Sn Rutherford cables under transverse stress from a single-wire experiment

Phys. Rev. Research 2, 013211 (2020)

The development of high-field accelerator magnets capable of providing 16-T dipolar fields is an indispensable technological breakthrough needed for the 100-TeV energy frontier targeted by the Future Circular ...

Design of van der Waals interfaces for broad-spectrum optoelectronics

Nature Materials volume 19, pages 299–304 (2020)

Van der Waals (vdW) interfaces based on 2D materials are promising for optoelectronics, as interlayer transitions between different compounds allow tailoring of the spectral response over a broad range....

Synthetic Semimetals with van der Waals Interfaces

Nano Lett. 2020, 20, 2, 1322–1328

The assembly of suitably designed van der Waals (vdW) heterostructures represents a new approach to produce artificial systems with engineered electronic properties. Here, we apply this strategy to realize...

Holographic imaging of the complex charge density wave order parameter

Phys. Rev. Research 1, 033114 (2019)

Combining real space and reciprocal space analysis of scanning tunneling microscopy images of transition metal dichalcogenides, we obtain real space maps of the amplitude, phase and periodicity of the complex ...

Low-temperature monoclinic layer stacking in atomically thin CrI3 crystals

2D Materials. 2020, vol. 7, no. 1, 015007

Chromium triiodide, CrI3, is emerging as a promising magnetic two-dimensional semiconductor where spins are ferromagnetically aligned within a single layer. Potential applications in spintronics...

High sensitivity variable-temperature infrared nanoscopy of conducting oxide interfaces

Nature Communications volume 10, 2774 (2019)

Probing the local transport properties of two-dimensional electron systems (2DES) confined at buried interfaces requires a non-invasive technique with a high spatial resolution operating in a broad...

High sensitivity variable-temperature infrared nanoscopy of conducting oxide interfaces

Nature Communications volume 10, 2774 (2019)

Probing the local transport properties of two-dimensional electron systems (2DES) confined at buried interfaces requires a non-invasive technique with a high spatial resolution operating in a broad...

Generation of 25 T with an all-superconducting magnet system: field profile and field quality measurements of a layer-wound 4 T REBCO insert coil for a 21 T LTS magnet

Superconductor Science and Technology 32,  7, 075005 (2019)

High temperature superconductors, especially rare-earth barium copper oxide (REBa2Cu3O7−x or REBCO) tapes are an enabling technology for magnetic fields beyond 23.5 T, the limit of the existing technology...

Thickness-Dependent Perovskite Octahedral Distortions at Heterointerfaces

Nano Lett. 2019, 19, 6, 4188–4194

In this study, we analyze how the octahedral tilts and rotations of thin films of LaNiO3 and LaAlO3 grown on different substrates, determined using synchrotron X-ray diffraction-measured ...

Energy-dependent spatial texturing of charge order in 1T-CuxTiSe2

Phys. Rev. B 99, 155133 (2019)

Scanning tunneling microscopy unveils an unusual energy dependent CDW pattern in Cu intercalated TiSe2. It is a direct manifestation of a large doping dependent CDW gap opening below the Fermi...

Charge-transfer insulation in twisted bilayer graphene

Phys. Rev. B 98, 235158 (2018)

The discovery of superconductivity and Mott insulation in twisted bilayer graphene has inspired this work, where we show that the correlated insulator state stems from a macroscopic charge transfer between AA ...

A spin-orbit playground: surfaces and interfaces of transition metal oxides

Reports on Progress in Physics 82, 012501 (2018)

Within the last twenty years, the status of the spin–orbit interaction has evolved from that of a simple atomic contribution to a key effect that modifies the electronic band structure of materials. It is...

Measurement of the Dynamical Structure Factor of a 1D Interacting Fermi Gas

We present measurements of the dynamical structure factor Sðq;ωÞ of an interacting one-dimensional Fermi gas for small excitation energies. We use the two lowest hyperfine levels of the 6Li atom to form a...

Rare-earth nickelates RNiO3: thin films and heterostructures

Reports on Progress in Physics. 2018, vol. 81, no. 046501

This review stands in the larger framework of functional materials by focussing on heterostructures of rare-earth nickelates, described by the chemical formula RNiO3 where R is a trivalent rare-earth...

Structural analysis of LaVO3 thin films under epitaxial strain

APL Materials 6, 046102 (2018)

Rare earth vanadate perovskites exhibit a phase diagram in which two different types of structural distortions coexist: the strongest, the rotation of the oxygen octahedra, comes from the small tolerance...

Observation of Caroli–de Gennes–Matricon Vortex States in YBa2Cu3O7-δ

Phys. Rev. Lett. 119, 237001 (2017)

Detailed scanning tunneling microsccopy and spectroscopy and original model calculations reveal the long sought after electronic signature of the vortex cores in a high temperature copper oxyde d-wave...

Dimensional crossover of the charge density wave transition in thin exfoliated VSe2

2D Materials 4, 041005 (2017)

Scanning tunneling microscopy of in-situ exfoliated VSe2 reveals a non monotonic thickness dependence of the charge density wave (CDW) order parameter and phase transition temperature. Both...

Subatomic electronic feature from dynamic motion of Si dimer defects in Bi nanolines on Si(001)

Phys. Rev. B 96, 075304

Reduced dimensions can give rise to surprising effects. While a long exposure time photograph of a macroscopic moving object appears blurred, scanning tunneling microscopy images of flipping Si dimer defects...

Ferroelectricity woos pairing

Nature Physics volume 13, pages 624–625 (2017)

Can ferroelectricity and superconductivity occur simultaneously? Can ferroelectricity boost the superconducting critical temperature? Writing in Nature Physics, Carl Rischau and colleagues1 report...

Electrically controlled terahertz magneto-optical phenomena in continuous and patterned graphene

Nature Communications volume 8, 14626 (2017)

The magnetic circular dichroism and the Faraday rotation are the fundamental phenomena of great practical importance arising from the breaking of the time reversal symmetry by a magnetic field. In most...

Conductivity and Local Structure of LaNiO3 Thin Films

Advanced materials. 2017, vol. 29, no. 18, 1605197

A marked conductivity enhancement is reported in 6–11 unit cell LaNiO3 thin films. A maximal conductivity is also observed in ab initio calculations for films of the same thickness. In agreement with...

Stripe and Short Range Order in the Charge Density Wave of 1T-CuxTiSe2

Phys. Rev. Lett. 118, 017002

Combining scanning tunneling microscopy (STM) and density functional theory, we unambiguously identify Cu intercalated on the octahedral site in the van der Waals gap of 1T-CuxTiSe2. STM ...

Efficient spin-to-charge conversion in the 2D electron liquid at the LAO/STO interface

Europhysics Letters, Volume 116, Number 1

Spin-to-charge conversion using the inverse Rashba-Edelstein effect is measured in the 2D electron liquid existing at the interface between LaAlO3 and SrTiO3. The effect is found to be...

Fermi polaron-polaritons in charge-tunable atomically thin semiconductors

Nature Physics volume 13, pages 255–261 (2017)

The dynamics of a mobile quantum impurity in a degenerate Fermi system is a fundamental problem in many-body physics. The interest in this field has been renewed due to recent ground-breaking experiments with ...

Fermi Arcs in the candidate type-II Weyl semimetal MoTe2

Phys. Rev. X 6, 031021 (2016)

We report a combined experimental and theoretical study of the candidate type-II Weylsemimetal MoTe2. Using laser-based angle-resolved photoemission, we resolve multiple distinct Fermi arcs. All surface...

Ferroelectric domains in epitaxial PbxSr1−xTiO3 thin films investigated using X-ray diffraction and piezoresponse force microscopy

APL Materials. 2016, vol. 4, no. 8, 086105

We present a detailed study of compressively strained PbxSr1−xTiO3 thin films grown by off-axis radio frequency magnetron sputtering on (001)-oriented Nb-doped...

Negative capacitance in multidomain ferroelectric superlattices

Nature volume 534, pages 524–528 (2016)

The stability of spontaneous electrical polarization in ferroelectrics is fundamental to many of their current applications, which range from the simple electric cigarette lighter to non-volatile random...

Built-in voltage in thin ferroelectric PbTiO3 films: the effect of electrostatic boundary conditions

New Journal of Physics, Volume 18, April 2016

We have studied the built-in voltage in heterostructures composed of ferroelectric PbTiO3 and dielectric spacers of SrTiO3, grown on SrTiO3 substrates with SrRuO3...

Interlayer coupling through a dimensionality-induced magnetic state

Nature Communications volume 7, 11227 (2016)

Dimensionality is known to play an important role in many compounds for which ultrathin layers can behave very differently from the bulk. This is especially true for the paramagnetic metal LaNiO3,...

Electron–phonon interactions in the SrTiO3(001) 2D electron liquid

Nature Mater 15, 835–839 (2016)

We use the prototypical two-dimensional electron liquid (2DEL) at the SrTiO3(001) surface to reveal a remarkably complex evolution of electron–phonon coupling with the tunable carrier density of this...

Revisiting the vortex-core tunnelling spectroscopy in YBa2Cu3O7−δ

Nat. Commun. 7, 11139 (2016)

Scanning tunnelling spectroscopy on very homogeneous Y123 at 0.4K lift the veil on the vortex core spectroscopy. We find that the subgap features which have been challenging theoretical modelling for over...

Research Update: Conductivity and beyond at the LaAlO3/SrTiO3 interface

APL Materials 4, 060701 (2016)

In this review, we focus on the celebrated interface between two band insulators, LaAlO3 and SrTiO3, that was found to be conducting, superconducting, and to display a strong spin-orbit coupling. We discuss...

Characterization of atomic force microscopy written conducting nanowires at LaAlO3/SrTiO3 interfaces

Appl. Phys. Lett. 108, 061604 (2016)

The realization of conducting nanostructures at the interface between LaAlO3 and SrTiO3 is an important step towards the realization of devices and the investigation of exotic physical regimes. We present...

Enhanced superconductivity due to forward scattering in FeSe thin films on SrTiO3 substrates

New J. Phys. 18, 022001 (2016)

Our theory provides one of the most prominent explanations of enhanced superconductivity in single layer FeSe on STO substrates. It has inspired novel experiments (for example on the phonon linewidth) and...

Explicit Local Integrals of Motion for the Many-Body Localized State

Phys. Rev. Lett. 116, 010404 (2016)

We provided a novel method to compute integrals of motion in a quantum system with interactions and disorder, based on ‘displacement transformations’. Unlike others, our method can also compute the...

Structure of Self-Assembled Mn Atom Chains on Si(001)

Phys. Rev. Lett. 115, 256104

Combining scanning tunneling microscopy, atomic force microscopy, and density functional theory we find that a simple necklacelike chain of single Mn atoms reproduces all the prominent features of Mn atom...

Positive Effect of an Internal Depolarization Field in Ultrathin Epitaxial Ferroelectric Films

Adv. Electron.Mater.2016, 2, 1500288

The effect of intentionally introducing a large depolarization field in (001)-oriented, epitaxial Pb(Zr0.2TiO0.8)O3 (PZT) ultrathin films grown on...

Collapse of the Mott gap and emergence of a nodal liquid in lightly doped Sr2IrO4

Phys. Rev. Lett. 115, 176402 (2015)

We report ARPES experiments on the electron doped Heisenberg antiferromagnet (Sr1−xLax)2IrO4. For a doping level of x=0.05, we find an unusual metallic state with coherent nodal excitations and an antipodal ...

Interfacial Control of Magnetic Properties at LaMnO3/LaNiO3 Interfaces

Nano Lett. 2015, 15, 11, 7355–7361

The functional properties of oxide heterostructures ultimately rely on how the electronic and structural mismatches occurring at interfaces are accommodated by the chosen materials combination. We discuss...

Impurity Bound States and Greens Function Zeroes as Local Signatures of Topology

Phys. Rev. B 92, 085126 (2015)

The classification of topological phases of matter is of utmost importance in modern condensed matter physics. We provide a simple yet effective way of observing topology by means of the experimentally...

Scanning tunneling microscopy of the charge density wave in 1T−TiSe2 in the presence of single atom defects

Phys. Rev. B 92, 081101(R)

The charge density wave (CDW) in 1T-TiSe2 is imaged by scanning tunneling microscopy in the presence of single atom defects. The detailed identification of the defects by means of density...

Glassy dynamics in geometrically frustrated Coulomb liquids without disorder

Phys. Rev. Lett. 115, 025701 (2015)

Our theory has been experimentally confirmed in new experiments on organic electron glasses, and provides a new benchmark for glassy theories. At the moment, this work provides the dominant explanation for...

Spatially resolved ultrafast magnetic dynamics initiated at a complex oxide heterointerface

Nature Mater 14, 883–888 (2015)

Static strain in complex oxide heterostructures has been extensively used to engineer electronic and magnetic properties at equilibrium. In the same spirit, deformations of the crystal lattice with light may...

Carrier Density Control of the SrTiO3 (001) surface 2DEG

Advances Materials, 27 (26), 3894-3899 (2015)

The origin of the two-dimensional electron gas (2DEG) stabilized at the bare surface of SrTiO3 (001) is investigated. Using high-resolution angle resolved photoemission and core level spectroscopy we show...

Optically active quantum dots in monolayer WSe2

Nature Nanotechnology volume 10, pages 491–496 (2015)

Semiconductor quantum dots have emerged as promising candidates for the implementation of quantum information processing, because they allow for a quantum interface between stationary spin qubits and...

Giant oscillating thermopower at oxide interfaces

Nature Communications volume 6, 6678 (2015)

Understanding the nature of charge carriers at the LaAlO3/SrTiO3 interface is one of the major open issues in the full comprehension of the charge confinement phenomenon in oxide...

Tailoring the electronic transitions of NdNiO3 films through (111)pc oriented interfaces

APL Materials 3, 062506 (2015)

Bulk NdNiO3 and thin films grown along the pseudocubic (001)pc axis display a 1st order metal to insulator transition (MIT) together with a Néel transition at T = 200 K. Here, we show...

Coherent quasiparticles in lightly doped Sr3Ir2O7

Phys. Rev. Lett. 113, 256402 (2014)

We characterize the electron doping evolution of (Sr1−xLax)3Ir2O7. Concomitant with the metal insulator transition around x≈0.05 we find the emergence of coherent quasiparticle states forming a closed...

Control of a Two-Dimensional Electron Gas on SrTiO3 (111) by Atomic Oxygen

Phys. Rev. Lett. 113, 177601 (2014)

We report on the formation of a two-dimensional electron gas (2DEG) at the bare surface of (111) oriented SrTiO3. Angle resolved photoemission experiments reveal highly itinerant carriers with a sixfold...

Tuning of the Depolarization Field and Nanodomain Structure in Ferroelectric Thin Films

Nano Lett. 2014, 14, 8, 4205–4211

The screening efficiency of a metal–ferroelectric interface plays a critical role in determining the polarization stability and hence the functional properties of ferroelectric thin films. Imperfect...

Doping Nature of Native Defects in 1T−TiSe2

Phys. Rev. Lett. 112, 197001 (2014)

The structural and doping nature of native atomic defects in TiSe2 are identified and characterized using scanning tunneling microscopy or spectroscopy and ab initio calculations. The dominant single atom...

Fabricating superconducting interfaces between artificially grown LaAlO3 and SrTiO3 thin films

APL Materials 2, 012102 (2014)

Realization of a fully metallic two-dimensional electron gas (2DEG) at the interface between artificially grown LaAlO3 and SrTiO3 thin films has been an excitingchallenge. Here we present for the first time...

Half-filled orbital and unconventional geometry of a common dopant in Si(001)

Phys. Rev. B 88, 035440 (2013)

In this study, we find that isolated heavy dopants behave entirely different at the surface compared to the bulk and to lighter dopants. The common light impurity P replaces individual Si atoms and maintains...

Scalable Patterning of One-Dimensional Dangling Bond Rows on Hydrogenated Si(001)

ACS Nano 2013, 7, 5, 4422–442

Hydrogen dangling bonds are highly reactive and their selective exposure on hydrogenated Si(001) using scanning probes is developing as a powerful lithography to pattern molecules and atoms. We have found...

Tunable conductivity threshold at polar oxide interfaces

Nature Communications volume 3, 932 (2012)

The physical mechanisms responsible for the formation of a two-dimensional electron gas at the interface between insulating SrTiO3 and LaAlO3 have remained a contentious subject since...

Piezoresistance in Silicon at Uniaxial Compressive Stresses up to 3 GPa

Phys. Rev. Lett. 108, 256801 (2012)

Measuring the piezoresistance in p-type silicon up to 3GPa, we found it to decrease with compressive stress beyond the predicted saturation. This result has potential implications for the Si technology...

Electrostatic Coupling and Local Structural Distortions at Interfaces in Ferroelectric/Paraelectric Superlattices

Nano Lett. 2012, 12, 6, 2846–2851

The performance of ferroelectric devices is intimately entwined with the structure and dynamics of ferroelectric domains. In ultrathin ferroelectrics, ordered nanodomains arise naturally in response to the...

Exchange bias in LaNiO3–LaMnO3 superlattices

Nature Materials volume 11, 195–198 (2012)

The wide spectrum of exotic properties exhibited by transition-metal oxides stems from the complex competition between several quantum interactions. The capacity to select the emergence of specific phases at...

Charge density waves in the graphene sheets of the superconductor CaC6

Nature Communications. 2011, vol. 2, 558

One dimensional charge density wave discovered by scanning tunneling microscopy in CaC6, a superconducting graphite intercalate compound.

Endotaxial Si nanolines in Si(001):H

Phys. Rev. B 84, 035328 (2011)

A one dimensional electronic state has been uncovered along the core of a self assembled endotaxial Si nanoline at the Si(001):H surface, with a range of promising properties to explore 1D physics.

Imaging oxygen defects and their motion at a manganite surface

Nature Communications. 2011, vol. 2, 212

The oxygen migration scenario for electroresistive switching in manganites gets new support. Mobile oxygen adatoms and defects have been observed by scanning tunneling microscopy with atomic resolution at the ...

Interface Physics in Complex Oxide Heterostructures

Annual Review of Condensed Matter Physics. 2011, vol. 2, no. 1, p. 141-165

Complex transition metal oxides span a wide range of crystalline structures and play host to an incredible variety of physical phenomena. High dielectric permittivities, piezo-, pyro-, and ferroelectricity...

Giant Piezoresistance Effects in Silicon Nanowires and Microwires

Phys. Rev. Lett. 105, 226802 (2010)

Migrating surface charges can simulate the giant piezoresistance observed in silicon nano- and micro-structures. See also comments in APS Physics Synopsis, Nature Materials Research Highlight and Physics...

Hands-on inspiration for science

Nature Materials 8, 245–247 (2009)

The PhysiScope draws the attention of Nature Materials.

Electric field control of the LaAlO3/SrTiO3 interface ground state

Nature volume 456, pages 624–627 (2008)

Interfaces between complex oxides are emerging as one of the most interesting systems in condensed matter physics. In this special setting, in which translational symmetry is artificially broken, a variety of ...

Improper ferroelectricity in perovskite oxide artificial superlattices

Nature. 2008, vol. 452, no. 7188, p. 732-736

Ferroelectric thin films and superlattices are currently the subject of intensive research because of the interest they raise for technological applications and also because their properties are of...

Giant Room-Temperature Piezoresistance in a Metal-Silicon Hybrid Structure

Phys. Rev. Lett. 100, 145501 (2008)

Giant piezoresistance observed in a metal silicon hybrid structure. Article was featured in AIP Physics News Update.

Superconducting Interfaces Between Insulating Oxides

Science. 2007, vol. 317, no. 5842, p. 1196-1199

At interfaces between complex oxides, electronic systems with unusual electronic properties can be generated. We report on superconductivity in the electron gas formed at the interface between two insulating...