Ana Akrap: Exploring topological matter by optical spectroscopy

A decade ago materials with nontrivial topologies in their band structure made a grand entrance into the condensed matter physics arena. Soon thereafter, it became clear that topological states of matter were surprisingly widespread. The aim of this seminar is to give an overview of our ongoing exploration in the realm of topological matter. One example are 3D Dirac semimetals. My talk will focus on cadmium arsenide (Cd3As2), recently identified as a 3D Dirac semimetal in which two Dirac nodes are separated near the Gamma point. Our optical and magneto-optical experiments resolve the conundrum of the Dirac cones' energy scale. We also uncover a different, unsuspected kind of massless particles at higher energies. Finally, micrometer-scale optical spectroscopy shines light onto the inherent material complexity.