# Regensburg 2019 – wissenschaftliches Programm

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# TT: Fachverband Tiefe Temperaturen

## TT 37: Topological Semimetals - Theory (joint session TT/MA)

### TT 37.5: Vortrag

### Mittwoch, 3. April 2019, 10:30–10:45, H22

**Evolution of surface states of the Luttinger semimetal under strain and inversion symmetry breaking: Dirac and Weyl semimetals** — •Benedikt Mayer, Maxim Kharitonov, and Ewelina Hankiewicz — Institute for Theoretical Physics and Astrophysics, University of Würzburg, 97074 Würzburg, Germany

Luttinger semimetal, the quadratic-node semimetal for *j*=3/2 electrons under full cubic symmetry, is the parent highest-symmetry minimal model for a variety of topological and/or strongly correlated materials, such as HgTe, α-Sn,
and iridate compounds. Recently, Luttinger semimetal has been demonstrated to exhibit surface states of topological origin that can be attributed to approximate chiral symmetry.
In the present work, we theoretically study the effect of the symmetry-lowering perturbations on these surface states within an analytical model.
Under compressive strain lowering rotational symmetry, Luttinger semimetal becomes a Dirac semimetal with a pair of double-degenerate linear nodes.
Breaking further inversion symmetry, the system turns into a Weyl semimetal, with each Dirac node split into four Weyl nodes.
We analyze the corresponding evolution of the surface states, connecting the surface-state structures in the linear regime near the nodes and in the quadratic regime of the Luttinger semimetal away from the nodes.
In particular, we demonstrate agreement of the Chern numbers with the chiralities of the surface states.