We are investigating low dimensional correlated electron systems by scanning probe microscopy and spectroscopy. Current scientific projects include i) Understanding the interplay between ordered electronic phases and superconductivity; ii) Thickness and strain dependent electronic properties in layered superconductors and charge density wave systems. iii) Tuning electronic properties by means of space charge doping. Materials of interest include transition metal dichalcogenides, cuprates, iron pnictides, graphitic materials and specifically designed functional electronic systems.
The prime experimental techniques are scanning tunneling microscopy (STM) and spectroscopy (STS) in combination with atomic force microscopy (AFM). We are operating three commercial instruments in ultrahigh vacuum (UHV) and variable temperature, two of them combining STM and AFM. An Omicron LT-STM is equipped with RHEED, LEED, XPS, a dedicated hydrogen cracker, an ion gun and a range of deposition sources. Two SPECS JT-STM, one standard and one with a 3 Tesla magnetic field plus a dedicated hydrogen cracker, an ion gun and a range of deposition sources. We also have two home-built instruments, one STM operating in a He3 cryostat reaching 0.4K, and a combined STM/AFM under final assembly in a variable temperature UHV system with a vector magnet (4T/9T). Our laboratory further features several preparation chambers, including a glove box and an UHV chamber to exfoliate layered van der Waals materials and deposit contacts and markers by shadow mask evaporation.
We are also actively developing the scanning probe technique itself, building a scan head with increased functionalities and a novel scheme to detect the spin polarization of the tunneling electrons by STM.