Electronic properties of Cu2(Zn, Cd)SnS4 determined by the high-field magnetotransport

Abstract

Resistivity, ρ(T), and magnetoresistance (MR) are investigated in the Cu2Zn1−x Cd x SnS4 single crystals for compositions x ≡ Cd/(Zn + Cd) = 0.15–0.24, in the temperature range of T ∼ 50–300 K in pulsed magnetic fields of B up to 20 T. The Mott variable-range hopping (VRH) conductivity is established within wide temperature intervals lying inside ΔT M ∼ 60–190 K for different x. The deviations from the VRH conduction, observable above and below ΔT M, are connected to the nearest-neighbor hopping regime and to the activation on the mobility threshold of the acceptor band (AB) with width W ≈ 16–46 meV. The joint analysis of ρ(T) and positive MR permitted determination of other important electronic parameters. These include the localization radius, α ≈ 19–30 Å, the density of the localized states, g(μ) ≈ (1.6–21) × 1017 meV−1 cm−3 at the Fermi level μ, and the acceptor concentration, N A ∼ (6–8) × 1019 cm−3, for various x and in conditions of different vicinity of the investigated samples to the metal–insulator transition. In addition, details of the AB structure, including positions of μ and of the mobility threshold, E c, are found depending on the alloy composition.