Drastic pressure effect on the extremely large magnetoresistance in WTe2: quantum oscillation study

TL;DR

This study investigates how high pressure affects the large magnetoresistance in WTe2 by analyzing quantum oscillations, revealing pressure-induced changes in Fermi surfaces that diminish magnetoresistance.

Contribution

It provides new insights into pressure effects on Fermi surfaces and magnetoresistance in WTe2, highlighting the role of electron-hole balance in extreme magnetoresistance.

Findings

Magnetoresistance decreases significantly under high pressure.

Two Fermi surface pockets persist at high pressure.

Pressure causes increasing disparity between Fermi surface pockets.

Abstract

The quantum oscillations of the magnetoresistance under ambient and high pressure have been studied for WTe$_2$ single crystals, in which extremely large magnetoresistance was discovered recently. By analyzing the Shubnikov-de Haas oscillations, four Fermi surfaces are identified, and two of them are found to persist to high pressure. The sizes of these two pockets are comparable, but show increasing difference with pressure. At 0.3 K and in 14.5 T, the magnetoresistance decreases drastically from 1.25 $\times$ $10^5$\% under ambient pressure to 7.47 $\times$ $10^3$\% under 23.6 kbar, which is likely caused by the relative change of Fermi surfaces. These results support the scenario that the perfect balance between the electron and hole populations is the origin of the extremely large magnetoresistance in WTe$_2$.