Highly mobile carriers in a candidate of quasi-two-dimensional topological semimetal AuTe2Br

Abstract

We report the crystal and electronic structures of a non-centrosymmetric quasi-two-dimensional (2D), candidate of topological semimetal AuTe2Br. The Fermi surface of this layered compound consists of 2D-like, topological trivial electron and non-trivial hole pockets which host a Dirac cone along the kz direction. Our transport measurements on the single crystals show highly anisotropic, compensated low-density electrons and holes, both of which exhibit ultrahigh mobility at a level of 10 5 cm 2 V −1 s −1 at low temperature.The highly mobile, compensated carriers lead a non-saturated, parabolic magnetoresistance as large as 3 × 10 5 in single-crystalline AuTe2Br in a magnetic field up to 58 T.

Review of Anisotropic 2D Materials: Controlled Growth, Optical Anisotropy Modulation, and Photonic Applications

“…The ternary halide AuTe 2 Br has emerged as a novel topological semimetal. [ 70 ] In 2D AuTe 2 Br, the Au and Te atoms form BP‐like puckered layer, while the halogen atoms are inserted in the interlayer spacing. [ 57 ] The asymmetric structure leads to highly anisotropic mobility and Raman scattering.…”

Confinement Effect Driven Quantum Spin Hall Effect in Monolayer AuTe2Cl

“…1(f) reveals a semimetal character, where the valence band is partially empty resulting in a hole pocket along Γ−Y, while the conduction band is partially filled resulting in a electron pocket along X−M. This has been confirmed in transport experiments [27]. When the SOC is neglected, there is a Dirac point along Γ−Y direction at 0.25 eV above the Fermi level formed by the p x and p z band crossing.…”

“…From all these compelling evidences, we thus conclude that the monolayer AuTe 2 Cl is a QSH insulator with a topological band gap about 10 meV. It should be noted that the 3D bulk AuTe 2 Cl has been experimentally synthesied [25][26][27]. We expect the monolayer system can be exfoliated from its 3D counterpart, or from molecular beam epitaxy growth method.…”

“…The bulk compound AuTe 2 Cl has been synthesized in experiment [25][26][27], which adopts a layered orthorhombic structure (D 2h point group) and lattice constant a = 4.02Å, b = 11.87Å, c = 8.77Å with the nonsymmorphic space group Cmcm (No. 63), as shown in Fig.…”

Anisotropic Raman spectrum and transport properties of AuTe2Br flakes

“…Angular dependence of Shubnikov-de Haas oscillations was studied [4] and the Fourier transform shows multiple frequencies and great anisotropy of the Fermi surface over different directions, revealing the 2D nature of AuTe 2 X compounds [5]. Recently AuTe 2 Br gained attention again due to its novel band structure [6]. Band calculation suggests AuTe 2 Br is a topological semimetal whose Fermi surface mainly constitutes of one hole-like and one electron-like pocket, and there exists a band-crossing Dirac cone in the hole pocket near the gamma point above the Fermi energy [6].…”