Tensile Strained Gray Tin: a New Dirac Semimetal for Observing Negative Magnetoresistance with Shubnikov-de-Haas Oscillation

TL;DR

This paper proposes that tensile strained gray tin is a promising Dirac semimetal for observing negative magnetoresistance and Shubnikov-de-Haas oscillations at relatively low magnetic fields, due to its tunable Dirac points and high mobility.

Contribution

It identifies gray tin as a strain-tunable Dirac semimetal with observable chiral magnetic effects, expanding the material options for studying topological phenomena.

Findings

Gray tin becomes a Dirac semimetal under tensile strain.

Tunable Dirac points and Fermi arcs are observed.

Large negative magnetoresistance and SdH oscillations are expected.

Abstract

The extremely stringent requirement on material quality has hindered the investigation and potential applications of exotic chiral magnetic effect in Dirac semimetals. Here, we propose that gray tin is a perfect candidate for observing the chiral anomaly effect and Shubnikov-de-Haas (SdH) oscillation at relatively low magnetic field. Based on effective $k.p$ analysis and first-principles calculations, we discover that gray tin becomes a Dirac semimetal under tensile uniaxial strain, in contrast to a topological insulator under compressive uniaxial strain as known before. In this newly found Dirac semimetal state, two Dirac points which are tunable by tensile [001] strains, lie in the $k_z$ axis and Fermi arcs appear in the (100) surface. Duo the low carrier concentration and high mobility of gray tin, a large chiral anomaly induced negative magnetoresistance and a strong SdH oscillation are anticipated in this half of strain spectrum. Comparing to other Dirac semimetals, the proposed Dirac semimetal state in the nontoxic elemental gray tin can be more easily manipulated and accurately controlled. We envision that gray tin provides a perfect platform for strain engineering of chiral magnetic effects by sweeping through the strain spectrum from positive to negative and vice versa.