"Towards a microscopic understanding of quantum matter" Dr. Freek Massee

Dr. Freek Massee
Postdoc / Marie Curie fellow
CNRS / University Paris-Sud
 

Abstract

For a deeper understanding of quantum matter, e.g. high temperature superconductors, heavy fermion systems, topological matter, etc., local information is essential, in particular on the scale where the action occurs: the atoms, the electrons and spins. With atomic scale access to the atomic structure, the local density of states and the spin, scanning tunnelling microscopy is an ideal experimental probe to obtain such information. Moreover, by using Fourier transform techniques, not only real space, but also momentum space information is obtained.

In this talk, I will first discuss the atomic scale effect of heavy ion irradiation of the iron based superconductor Fe(Se,Te) on superconductivity and vortex pinning [1], exemplifying the real space power of scanning tunnelling microscopy. Then, to illustrate the momentum space capabilities, I will show how to determine the band- and superconducting gap structure of the heavy Fermion superconductor CeCoIn5 [2].

Whereas both these studies probe time-independent properties, the dynamics of quantum matter often contain important clues to the mechanism driving their exotic and technologically very relevant properties. In the last part of the talk, I will discuss the development and application of a high frequency, and shot-noise, compatible scanning tunnelling microscope, which will make the dynamics and out-of-equilibrium properties accessible at the atomic scale.

[1] F. Massee & P. O. Sprau et al., Science Advances 1, e1500033 (2015)
[2] M. P. Allan & F. Massee et al., Nature Physics 9, 468 (2013)

Biography

I obtained my PhD degree in physics in the field of experimental condensed matter physics from the University of Amsterdam, The Netherlands on April 12, 2011. After a short postdoc in a collaboration between the University of Amsterdam, the Foundation for Fundamental Research on Matter (FOM) and ASML, I moved to Cornell University in Ithaca, New York (USA) for a three-year postdoc in the group of J. C. Séamus Davis. Since 2015 I am employed as a Marie-Curie fellow at the National Science Research Center (CNRS) and the University of Paris-Sud in Orsay, France.