Negative longitudinal magnetoresistance in gallium arsenide quantum wells

Abstract

Negative longitudinal magnetoresistances (NLMRs) have been recently observed in a variety of topological materials and often considered to be associated with Weyl fermions that have a defined chirality. Here we report NLMRs in non-Weyl GaAs quantum wells. In the absence of a magnetic field the quantum wells show a transition from semiconducting-like to metallic behaviour with decreasing temperature. We observe pronounced NLMRs up to 9 Tesla at temperatures above the transition and weak NLMRs in low magnetic fields at temperatures close to the transition and below 5 K. The observed NLMRs show various types of magnetic field behaviour resembling those reported in topological materials. We attribute them to microscopic disorder and use a phenomenological three-resistor model to account for their various features. Our results showcase a contribution of microscopic disorder in the occurrence of unusual phenomena. They may stimulate further work on tuning electronic properties via disorder/defect nano-engineering.

Longitudinal and transverse magnetoresistance of SrTiO3with a single closed Fermi surface

“…When these terms make positive contributions, σ zz is an increasing function with respect to B, resulting in a negative ∆ρ zz . Recently, negative longitudinal MR has been discussed in connection with the topology of materials and the chiral anomaly [22][23][24][25]. The negative longitudinal MR discussed here is not related to topology or chiral anomaly, but is due to the warp in Fermi surfaces.…”

Angular dependence of Hall effect and magnetoresistance in SrRuO3−SrIrO3 heterostructures

“…The negative longitudinal magnetoresistance (LMR) could suggest the manifestation of Weyl fermions due to a chiral imbalance, as observed by Takiguchi et al [60] in high-quality SRO thin films. Microscopic disorder, for example, interface roughness, could also lead to a negative LMR [61]. When tilting the magnetic field perpendicular to the current (tilt angle β) the MR shows a completely different behavior [see Figs.…”

Negative magnetoresistance in Dirac semimetal Cd3As2 with in-plane magnetic field perpendicular to current

“…The competition with orbit-related positive MR might also smear the mechanism. Nevertheless, the spatial disorder and distorted current paths exist in our sample, which would necessarily involve conductivity fluctuation [39][40][41] or carrier puddles. [32] In the meantime, microscopic disorder islands, anisotropy of lattice and Fermi velocity need to be carefully investigated in further research.…”