Non-saturating Quantum Magnetization in Weyl semimetal TaAs

TL;DR

This paper demonstrates that Weyl semimetal TaAs exhibits non-saturating magnetization in strong magnetic fields, providing a thermodynamic signature for identifying 3D massless Weyl fermions, which differs from conventional massive carriers.

Contribution

It introduces a new thermodynamic criterion based on magnetization behavior to detect Weyl fermions in topological materials, supported by experimental and theoretical analysis.

Findings

Observation of quasi-linear field-dependent transverse magnetization

Detection of strongly enhanced parallel magnetization in the quantum limit

Non-saturating magnetic response consistent with Weyl fermion theory

Abstract

Detecting the spectroscopic signatures of Dirac-like quasiparticles in emergent topological materials is crucial for searching their potential applications. Magnetometry is a powerful tool for fathoming electrons in solids, yet its ability for discerning Dirac-like quasiparticles has not been recognized. Adopting the probes of magnetic torque and parallel magnetization for the archetype Weyl semimetal TaAs in strong magnetic field, we observed a quasi-linear field dependent effective transverse magnetization and a strongly enhanced parallel magnetization when the system is in the quantum limit. Distinct from the saturating magnetic responses for massive carriers, the non-saturating signals of TaAs in strong field is consistent with our newly developed magnetization calculation for a Weyl fermion system in an arbitrary angle. Our results for the first time establish a thermodynamic criterion for detecting the unique magnetic response of 3D massless Weyl fermions in the quantum limit.