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 charge-density wave (CDW). In contrast to semiconductors such as Ge and Si with band gaps $\sim 1\mathrm{eV}$, 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 band structure parameters (transfer integrals, Fermi velocity) to be determined accurately. These parameters reveal the orbital quantization limit to be reached at $\sim 20\mathrm{T}$ in $(\mathrm{Per}{)}_{2}M(\mathrm{mnt}{)}_2$ salts, making them highly unlikely candidates for a recently proposed cascade of field-induced CDW states.

• Received 20 September 2004

DOI:https://doi.org/10.1103/PhysRevLett.94.106404