Origin of the Extremely Large Magnetoresistance in the Semimetal YSb

TL;DR

This study reveals that the semimetal YSb exhibits nearly perfect electron-hole compensation, which, combined with anisotropic multi-band effects, explains its extremely large magnetoresistance, challenging previous assumptions about its origin.

Contribution

The paper demonstrates that YSb has nearly perfect electron-hole compensation and uses an anisotropic multi-band model to explain its large magnetoresistance, providing new insights into XMR mechanisms.

Findings

YSb has a density ratio of 0.95 for electrons and holes.

Magnetoresistance can be quantitatively described by an anisotropic multi-band model.

Evolution of magnetoresistance with different Fermi pocket combinations elucidates XMR origin.

Abstract

Electron-hole (e-h) compensation is a hallmark of multi-band semimetals with extremely large magnetoresistance (XMR) and has been considered to be the basis for XMR. Recent spectroscopic experiments, however, reveal that YSb with non-saturating magnetoresistance is uncompensated, questioning the e-h compensation scenario for XMR. Here we demonstrate with magnetoresistivity and angle dependent Shubnikov - de Haas (SdH) quantum oscillation measurements that YSb does have nearly perfect e-h compensation, with a density ratio of $0.95$ for electrons and holes. The density and mobility anisotropy of the charge carriers revealed in the SdH experiments allow us to quantitatively describe the magnetoresistance with an anisotropic multi-band model that includes contributions from all Fermi pockets. We elucidate the role of compensated multi-bands in the occurrence of XMR by demonstrating the evolution of calculated magnetoresistances for a single band and for various combinations of electron and hole Fermi pockets.