Compensated semimetal LaSb with unsaturated magnetoresistance

TL;DR

This study combines spectroscopy and quantum oscillation measurements to analyze LaSb's electronic structure, revealing perfect carrier compensation and trivial topology, which explains its unsaturated extremely large magnetoresistance.

Contribution

It provides a comprehensive electronic structure analysis of LaSb, showing carrier compensation and trivial topology, advancing understanding of XMR mechanisms in semimetals.

Findings

LaSb has perfectly compensated electron and hole carriers.

LaSb is topologically trivial despite similarities to Weyl semimetals.

LaSb exhibits unsaturated quadratic extremely large magnetoresistance.

Abstract

By combining angle-resolved photoemission spectroscopy and quantum oscillation measurements, we performed a comprehensive investigation on the electronic structure of LaSb, which exhibits near-quadratic extremely large magnetoresistance (XMR) without any sign of saturation at magnetic fields as high as 40 T. We clearly resolve one spherical and one intersecting-ellipsoidal hole Fermi surfaces (FSs) at the Brillouin zone (BZ) center $\Gamma$ and one ellipsoidal electron FS at the BZ boundary $X$. The hole and electron carriers calculated from the enclosed FS volumes are perfectly compensated, and the carrier compensation is unaffected by temperature. We further reveal that LaSb is topologically trivial but share many similarities with the Weyl semimetal TaAs family in the bulk electronic structure. Based on these results, we have examined the mechanisms that have been proposed so far to explain the near-quadratic XMR in semimetals.