Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 21: Topological Semimetals 1

TT 21.5: Vortrag

Dienstag, 17. März 2020, 10:30–10:45, HSZ 103

Semi-Dirac state revealed in black phosphorus via high-pressure studies — •D. Rodriguez1, Q. Yan2, M. Dressel1, and E. Uykur111. Physikalisches Institut, Universität Stuttgart, 70569, Stuttgart, Germany — 2Department of Chemistry, Tsinghua University, Beijing 100084, China

Semi-Dirac materials are a class of Dirac/Weyl semimetals that display a two-feature energy dispersion: linear (relativistic) along one momentum direction and quadratic (non-relativistic) in the other direction. The realization of this unique state in real materials is still pending. One promising system is the black phosphorus (BP). It has been theoretically predicted that hydrostatic pressure can close the band gap, driving the system through several electronic transitions from a gapped insulator with inverted bands to a Dirac semimetal state. An intermediate phase exists though, the semi-Dirac state characterized by a gapless anisotropic spectrum dispersing linearly along its armchair direction and parabolically along the zigzag. Here, we report high-pressure infrared measurements of BP tuned successfully through the insulator-to-metal transition. Our optical conductivity results present a highly anisotropic behavior for different light polarization in the low energy range consistent with the theoretical predictions of a semi-Dirac state. Moreover, results indicate that Dirac state in BP has a 3D character rather than 2D.

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