Speaker: Prof. Shun-Qing Shen (Univ. of HK)

Abstract

Recently, negative longitudinal and positive in-plane transverse magnetoresistance have been observed in most topological Dirac/Weyl semimetals, and some other topological materials. Here we present a quantum theory of intrinsic magnetoresistance for three-dimensional Dirac fermions at a finite and uniform magnetic field B. In a semi-classical regime, it is shown that the longitudinal magnetoresistance is negative and quadratic of a weak field B while the in-plane transverse magnetoresistance is positive and quadratic of B. The relative magnetoresistance is inversely quartic of the Fermi wave vector and only determined by the density of charge carriers, irrelevant to the external scatterings in the weak scattering limit. This intrinsic anisotropic magnetoresistance is measurable in systems with lower carrier density and high mobility. In the quantum oscillation regime a formula for the phase shift in Shubnikov-de Hass oscillation is present as a function of the mobility and the magnetic field, which is useful for experimental data analysis.

Reference:

H. W. Wang, B. Fu, S. Q. Shen

Intrinsic Magnetoresistance in Three-Dimensional Dirac Materials, arXiv:1804.00246

H. Li, H.W. Wang, H. He, J. Wang, S. Q. Shen

Giant anisotropic magnetoresistance and planar Hall effect in the Dirac semimetal Cd₃ As₂, Phys. Rev. B 97, 201110 (R)(2018)

Time & Date: 15:00, June 20 (Wed.), 2018

Venue: Rm. N306, UCAS Teaching Building [View Map]