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Condensed Matter Seminar: Probing Band Topology by Quantum Oscillations
Speaker Prof. Philip Moll, Ecole Polytechnique Fédérale de Lausanne
Date 15 April 2021 (Thursday)
Time 16:00 - 17:30
Venue Online (Zoom)

A robust methodology to detect Dirac-Weyl fermions in topological semimetals by transport or thermodynamic measurements remains an open problem. It is often argued that a π-phase in quantum oscillations directly corresponds to the nontrivial Berry phase of topological semimetals. However, the oscillation phase is complicated by multiple contributing factors including the orbital magnetic moment, rendering such correspondences ambiguous for a substantial fraction of topological semimetals. Here, we propose to utilize the temperature dependence of the frequency, F(T), rather than the oscillation phase, as a hallmark signature of topology in quantum oscillations. At temperatures that are comparable to the cyclotron energy, F(T) encodes the energy-derivative of the cyclotron mass - a quantity that vanishes for conventional Schroedinger-type fermions, yet equals the inverse square of the Fermi velocity for Dirac-Weyl fermions. Cd3As2, Bi2O2Se and LaRhIn5 serve as testing grounds confirming our methodology. Our approach requires no ab-initio calculation as input, and is able to identify topological Fermi pockets which are small compared to the Brillouin-zone volume - both attributes being ideally suited to identify topological heavy-fermion materials.

[C. Guo; A. Alexandradinata et al, https://arxiv.org/abs/1910.07608]

Meeting Link: To request for meeting link, please write to phweb@ust.hk.