Landau quantization effects in the charge-density-wave system (Per)$_2M$(mnt)$_2$ (where $M=$Au and Pt)

TL;DR

This paper investigates how magnetic fields influence the electronic properties of a quasi-one-dimensional charge-density-wave system, revealing the parameters governing its bandstructure and the limits of orbital quantization.

Contribution

It provides a detailed analysis of Landau quantization effects in (Per)$_2M$(mnt)$_2$ salts, determining key electronic parameters and challenging the possibility of cascade CDW states.

Findings

Orbital quantization limit at ~20 T in (Per)$_2M$(mnt)$_2$ salts.

Magnetic field significantly alters the thermodynamic gap via Zeeman and Landau effects.

Electronic bandstructure parameters are accurately extracted from magnetic field dependence.

Abstract

A finite transfer integral $t_a$ orthogonal to the conducting chains of a highly one-dimensional metal gives rise to empty and filled bands that simulate an indirect-gap semiconductor upon formation of a commensurate charge-density-wave (CDW). In contrast to semiconductors such as Ge and Si with bandgaps $\sim 1$ eV, the CDW system possesses an indirect gap with a greatly reduced energy scale, enabling moderate laboratory magnetic fields to have a major effect. The consequent variation of the thermodynamic gap with magnetic field due to Zeeman splitting and Landau quantization enables the electronic bandstructure parameters (transfer integrals, Fermi velocity) to be determined accurately. These parameters reveal the orbital quantization limit to be reached at $\sim 20$ T in (Per)$_2M$(mnt)$_2$ salts, making them highly unlikely candidates for a recently-proposed cascade of field-induced charge-density wave states.