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TT: Fachverband Tiefe Temperaturen

TT 21: Topological Semimetals 1

TT 21.13: Vortrag

Dienstag, 17. März 2020, 12:45–13:00, HSZ 103

Strain engineered higher order topological phases for spin-3/2 Luttinger fermions — •Andras Szabo — MPIPKS Dresden

Higher order topological phases attracted a lot of attention in the recent years, and apart from elemental Bi have so far evaded experimental realization in electronic systems. I will present a potential path to use a Luttinger semimetal (LSM) in order to strain engineer a higher order topological Dirac semimetal (HOTDSM).

A Luttinger semimetal is constituted by effective spin-3/2 fermions and describes a bi-quadratic touching of Kramers degenerate valence and conduction bands. Several materials are believed to be sufficiently described by such model, including 227 pyrochlore iridates, half-Heuslers, HgTe and gray-Sn. Moreover, advances in experimental technology (piezoelectric-based apparatus, and growing samples on suitable substrates) present an infrastructure promising for the strain-engineering of such HOT phases.

I will show that certain nematic phases of a LSM, that can be induced by the application of external strain, describe a HOTDSM with topological hinge states along the strain direction. I will also argue that these phases are stable in the presence of sufficiently weak disorder, an inherent feature of real world material samples.