Magneto-transport and first principle study of strong topological insulator gray-arsenic

Abstract This article reports on the synthesis of single crystalline gray-Arsenic (As) via the Bismuth flux method. The x-ray Diffraction (XRD) pattern revealed the single phase of the as-grown crystal, which crystallized in the rhombohedral structure with the space group R-3m. The sharp XRD peaks observed on mechanically exfoliated thin flakes of the same ensured high crystallinity of the same with growth direction along the c-axis. The Energy Dispersive x-ray Analysis (EDAX) endorses the stoichiometric purity of the as-grown As single crystal. The Raman spectra are recorded to study the vibrational mode, which showed peaks at 196.2 cm −1 and 255.74 cm −1 , identified as E g and A 1g modes respectively, by DFT calculations. The as-grown crystal is further characterized for its electronic and magneto-transport properties. The resistivity versus temperature ( ρ -T) measurements illustrated its metallic nature throughout, right from 300 K down to 2 K. The measured residual resistivity ratio ( ρ 300K / ρ 2K ) of the sample is 180, which endorses the high metallic nature of the as-synthesized As single crystal. The transverse magnetic field-dependent resistivity ( ρ -H) measurements elucidated huge (10 4 %) magneto-resistance (MR) at 2 K and 14Tesla transverse magnetic fields, along with the SdH oscillations, indicating the presence of topological surface states. The non-trivial band topology and edge states in As are confirmed by first principle calculations. Not only do orbital projected bands show the signature of band inversion but also the Z2 invariant value (1,111) calculated by Wilson’s loop method affirms As to be a strong topological insulator (TI). Clear evidence of topological edge states in plane k z = 0 has been observed in surface state spectra and slab bands.