Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 20: Topological Semimetals II

TT 20.3: Vortrag

Montag, 12. März 2018, 15:30–15:45, A 053

Drumhead surface states in topological Dirac semimetal — •Andreas Leonhardt¹, Andreas Schnyder¹, Mehdi Biderang², Nimisha Raghuvanshi², and Alireza Akbari² — ¹Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany — ²Asia Pacific Center for Theoretical Physics, Pohang, Gyeongbuk 790-784, Korea

Dirac nodal line semimetals (DNLSMs) host a symmetry protected band crossing along a line in the BZ. The non-trivial Berry phase of the bulk within the nodal ring leads to localized drumhead surface states (DSSs) in the interior of the projection of the line node onto the surface BZ. Promising candidates to study the physics of DNLSMs are the compounds CaAg(P/As) and TlTaSe₂, which provide different SOC strengths and mechanisms.

Quasi particle interference (QPI) is dominated by surface states and provides a possibility to investigate the dispersion and spin polarization of the drumhead surface states. We present spin resolved QPI patterns from an effective low energy tight binding model for the most promising candidates of nodal line semimetals, together with a symmetry analysis of the resulting patterns with respect to the spin polarization of the DSSs, with a focus on the influence of SOC onto the line node and the surface states.

Furthermore, we investigate the effect of the non-trivial topology on non-linear optical response phenomena, where the Berry connection and curvature directly appear in terms of quadratic or higher order in the electric field.