Low-energy quasiparticle dynamics of three-dimensional Dirac materials

• Applicant: Professor Dr. Martin Dressel
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 286255266

The three-dimensional topological semimetals are in the focus of current solid-state research. Within a few years, the family of different topological electronic phases in bulk solids has rapidly grown: the Dirac- and Weyl-semimetal phases have recently been accompanied by the nodal-line, type-II, and multifold topological semimetals, which often have no direct analogues in high-energy physics. Research on these novel phases and on related quantum phenomena provides new strong ties between different branches of theoretical physics. On the other hand, potential applications of topological semimetals range from high-speed opto-electronic and spintronic devices to electron superlenses and catalysts. Both, fundamental interests and potential applications, are calling for thorough experimental investigations of these novel topological phases. Optical studies at infrared and terahertz frequencies are a proven tool to get insights into the dynamics of emerging exotic quasiparticles inherent to these phases at low energies. In our previous project, we successfully investigated the optical response of different Dirac and Weyl semimetals as well as of a few other topological materials. In the present project, we propose to study the response of most recently discovered topological semimetals of different families in order to pinpoint their low-energy properties arising from the emerging quasiparticles. In particular, we aim: 1) to identify those characteristic optical signatures of the type-II Weyl state, which would allow one to distinguish type-I and type-II semimetals; 2) to observe the chiral optical response arising from to the electrons in chiral bands situated at different energies; 3) to trace the influence of magnetic field on the chiral electronic bands. Our findings will provide robust and independent evidence for realization of the proposed topological states in the studied materials.

• DFG Programme: Research Grants
• Co-Investigator: Dr. Artem Pronin