Fermi Surface Reconstruction and Anisotropic Linear Magnetoresistance in the Charge Density Wave Topological Semimetal TaTe4

TL;DR

This study combines experimental and theoretical methods to map the Fermi surface of TaTe4, revealing its reconstruction due to charge density waves and the presence of anisotropic linear magnetoresistance, highlighting its potential as a topological semimetal.

Contribution

It provides the first comprehensive experimental mapping of the Fermi surface in the CDW phase of TaTe4 and links it to observed magnetoresistance phenomena, advancing understanding of topology and electron correlations.

Findings

Full reconstruction of the Fermi surface in the CDW phase.

Observation of a large orbit consistent with magnetic breakdown.

Persistent linear magnetoresistance across all field directions.

Abstract

Understanding the interplay between topology and correlated electron states is central to the study of quantum materials. TaTe$_4$ is a quasi-one-dimensional charge density wave (CDW) compound predicted to host topological phases, which makes it a model platform to explore this interplay. Here, we combine high-field magnetotransport measurements with density functional theory calculations to provide a comprehensive mapping of the Fermi surface (FS) of TaTe$_4$ in its CDW phase. Using multiple current-field geometries, we resolve the four largest of six pockets of the FS predicted by theory and find no evidence of non-CDW bands, highlighting the full reconstruction of the FS in the bulk. We identify a previously unobserved quasi-cylindrical pocket and uncover a large size orbit consistent with magnetic breakdown between reconstructed FS sheets, from which we estimate a CDW gap of $\sim$0.29~eV. Moreover, we observe a robust linear magnetoresistance that persists across all field directions when current flows perpendicular to the 1D chains along which the CDW is formed, with a distinct high-field linear regime emerging when field is along the chains. These findings establish TaTe$_4$ as a prototypical material to study the coexistence of correlation-driven reconstruction and topological electronic states.