Angle-dependent magnetoresistance as a sensitive probe of the charge density wave in quasi-one-dimensional semimetal Ta$_2$NiSe$_7$

TL;DR

This study demonstrates that angle-dependent magnetoresistance effectively probes charge density waves in quasi-one-dimensional materials, revealing how magnetic field orientation influences electronic states and symmetry properties.

Contribution

The paper introduces angle-dependent magnetoresistance as a sensitive method to investigate CDW behavior and underlying electronic anisotropy in Q1D systems, supported by first-principles calculations.

Findings

Magnetoresistance symmetry changes with magnetic field orientation below T_CDW.

Orbital effects follow lattice symmetry, while Pauli effects cause symmetry changes.

Fermi velocity anisotropy influences the magnetic field response of the CDW.

Abstract

The behavior of charge density wave (CDW) in an external magnetic field is dictated by both orbital and Pauli (Zeeman) effects. A quasi-one-dimensional (Q1D) system features Q1D Fermi surfaces that allow these effects to be distinguished, which in turn can provide sensitive probe to the underlying electronic states. Here we studied the field dependence of an incommensurate CDW in a transition-metal chalcogenide Ta2NiSe7 with a Q1D chain structure. The angle-dependent magnetoresistance (MR) is found to be very sensitive to the relative orientation between the magnetic field and the chain direction. With an applied current fixed along the b axis (the chain direction), the angle-dependent MR shows a striking change of the symmetry below T_CDW only for a rotating magnetic field in the ac plane. In contrast, the symmetry axis remains unchanged for other configurations (H in ab and bc plane). The orbital effect conforms to the lattice symmetry, while Pauli effect in the form of {\mu}B B / v_F can be responsible for such symmetry change, provided that the Fermi velocity v_F is significantly anisotropic and the nesting vector changes in a magnetic field, which is corroborated by our first-principles calculations. Our results show that the angle-dependent MR is a sensitive transport probe of CDW and can be useful for the study of low-dimensional systems in general.