Magnetic field-induced non-trivial Lifshitz transition in TaCo2Te2

TL;DR

This study uncovers an unconventional, temperature-dependent Lifshitz transition in TaCo2Te2 driven by magnetic field, involving Fermi-surface changes without symmetry breaking, revealing a new paradigm of joint temperature and magnetic control.

Contribution

It demonstrates a novel finite-temperature Lifshitz transition in TaCo2Te2 induced by magnetic field, without structural or magnetic phase transitions, expanding understanding of Fermi-surface topology control.

Findings

Continuous Fermi-surface renormalization at low temperatures

Transition sharply triggered by a critical magnetic field

Absence of structural or magnetic phase transitions

Abstract

Magnetic-field-driven Lifshitz transitions are typically considered zero-temperature phenomena involving Fermi-surface reconstruction without symmetry breaking. Here, we report an unconventional Lifshitz transition in TaCo2Te2 that emerges exclusively within a narrow finite-temperature window under cooperative tuning by both temperature and magnetic field. Bulk-sensitive transport and thermoelectric measurements demonstrate continuous Fermi-surface renormalization at low temperatures, where the transition is sharply triggered by a critical magnetic field. Crucially, neutron diffraction reveals the absence of structural or magnetic phase transitions, while angle-resolved photoemission spectroscopy shows no spectral anomalies in electronic structure without magnetic field. These observations constrain the mechanism to a Zeeman-driven process invisible to equilibrium probes, establishing a paradigm where Fermi-surface topology is jointly controlled by temperature and magnetic field.