Signatures of Nontrivial Topology in Weyl Semimetals and Fe-Based Superconductors
A key challenge in condensed matter is measuring the non-trivial topology responsible for novel phases. In this talk I will outline our recent efforts to reveal non-trivial topology with nonlinear optics and tunneling spectroscopy. First I will focus on our efforts to use nonlinear optics to measure the Berry connection in the Weyl semimetal TaAs. Specifically using new FIB fabricated mesoscopic devices we have succeeded in measuring photocurrents at room temperature associated with the electron chirality and Berry curvature. I will briefly touch on how these experiments offer hope for using Well semimetals for power generation and optical detection. In the second half I will discuss recent development in the study of FeTeSe, and in particular our 2D atomic heterostructures that reveal evidence for the unique higher order, superconducting topological state.