Large linear magnetoresistance in the Dirac semimetal TlBiSSe

Abstract

The mixed-chalcogenide compound TlBiSSe realizes a three-dimensional (3D) Dirac semimetal state. In clean, low-carrier-density single crystals of this material, we found Shubnikov-de Haas oscillations to signify its 3D Dirac nature. Moreover, we observed very large linear magnetoresistance (MR) approaching 10,000% in 14 T at 1.8 K, which diminishes rapidly above 30 K. Our analysis of the magnetotransport data points to the possibility that the linear MR is fundamentally governed by the Hall field; although such a situation has been predicted for highly-inhomogeneous systems, inhomogeneity does not seem to play an important role in TlBiSSe. Hence, the mechanism of large linear MR is an intriguing open question in a clean 3D Dirac system.

Linear magnetoresistance in metals: Guiding center diffusion in a smooth random potential

“…LMR in 3DDM exhibit puzzling features including (i) its occurrence when multiple Landau levels are occupied far from the extreme quantum limit, and (ii) arising in weakly disordered, high mobility samples. Further, LMR manifests consistently over a variety of 3DDM experiments, including in TiBiSSe [13], Cd 3 As 2 [14,15], Na 3 Bi [16], and TaAs [17], where chemical potential μ typically lies 0.1 eV above the Dirac point, hinting at a single underlying explanation.…”

“…Importantly, this mechanism naturally gives giant LMR under (i) and (ii) above, explaining the puzzling behavior [13][14][15][16][17]. The main requirement is that the disorder potential is smoothly varying on a scale ξ which is large as compared to the cyclotron radius r c .…”

“…Recently, giant LMR that lie outside the above two paradigms [see (i) and (ii) below] were reported in the newly discovered class of three-dimensional Dirac materials (3DDM) [13][14][15][16][17]. LMR in 3DDM exhibit puzzling features including (i) its occurrence when multiple Landau levels are occupied far from the extreme quantum limit, and (ii) arising in weakly disordered, high mobility samples.…”

“…Instead we are interested in LMR in 3DDM [13][14][15][16][17] which were observed in the metallic regime with carriers of a single type [14].…”

“…F is a dimensionless function that vanishes for |r − r | ξ . Lastly, we will be interested in weak disorder strength eV 0 < μ seen in 3DDM experiments [13][14][15][16][17] and recent estimates [22].…”