Day / Time
Date(s) - 17/05/2016
13 h 00 min - 14 h 30 min
Mardi 17 mai 2016 à 13.00
Ecole de physique
Professor Patrick Maletinsky
Department of Physics, University of Basel – CH
Single spin magnetometry of condensed matter systems
A single electronic spin can yield a close-to-ideal magnetometer to investigate magnetism in the solid state. Spins are natural magnetometers by virtue of their Zeeman response to magnetic fields. Quantum coherence and control can be exploited to taylor this response towards excellent magnetic field sensitivities. Lastly, the spins can be localised to atomic lengthscales, which enables nanoscale resolution in imaging. The electronic spin of the Nitrogen-Vacancy center in diamond has been identified as a particularly fruitful system to implement these concepts. It combines the above benefits with the ability of optical spin readout and initialisation and operates from cryogenic temperatures to ambient conditions, all while maintaining its exceptional quantum coherence properties. In the best case, this results in a non-invasive and quantitative magnetometer with single-spin sensitivity and nanoscale spatial resolution – a concept with many highly promising applications in science and technology.
My group at the University of Basel has in the past implemented various such NV-based quantum sensors with the goal of applying them to outstanding problems in condensed-matter and mesoscopic physics. In this talk, I will describe our experimental approach to such nanoscale NV magnetometry and discuss two systems, we currently investigate using this technique. Specifically, I will discuss an experiment, where we used scanning NV magnetometry to image individual vortices in the high-temperature superconductor YBa2Cu3O7, and some more recent results, where we were able to image and study domains in the magnetoelectric antiferromagnet Cr2O3.
In both cases, NV magnetometry allowed us to quantitatively determine essential material parameters of the systems under study – the London penetration depth for YBCO and the surface magnetic moment density for Cr2O3. Both are central quantities for the understanding of the respective materials, but both have also been notoriously hard or impossible to determine using previous experimental approaches. Our results therefore illustrate the power of NV magnetometry in determining local properties of electronic systems with nanoscale resolution and the promise our technology holds for future exploration of complex, condensed matter systems.