Hidden phases in quantum materials revealed at a surface

Speaker: Dr. Jisun Kim, Louisiana State University
Date & Time: Wednesday April 12th, 2:00pm - 3:00pm
Location: AMPEL 311
Local Contact: Doug Bonn/Sarah Burke
Intended Audience:

The last decade has seen extensive experimental and theoretical efforts to understand the physical properties of complex materials that exhibit strong coupling of electron, spin, lattice and orbital degrees of freedom. By tuning external parameters like temperature, pressure, magnetic field, and doping concentration, one can alter the delicate balance between these degrees of freedom, uncovering new phases. Creating a surface by cleaving complex layered materials perturbs the bulk properties revealing new phases, which are hidden phases in the bulk. In this talk, I will discuss how scanning tunneling microscopy/spectroscopy (STM/STS) reveals detailed surface structures and superconducting properties layer-by-layer in one of the newly-discovered Fe-based superconductors, Ca₁₀(Pt₄As₈)(Fe₂As₂)₅. The results indicate that altered charge balance and surface structure lead to different superconducting properties at the surface: an ordered structure with proper chemical stoichiometry is required in order to preserve superconductivity at the surface.

I will end with a discussion of how I envision pursuing my research interests in complex quantum materials using facilities available at Stewart Blusson Quantum Matter Institute. The advantage of low temperature STM with high magnetic field will be discussed with the focus on its ability to alter and probe the delicate balance in these materials.