Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8153197 | Journal of Magnetism and Magnetic Materials | 2018 | 6 Pages |
Abstract
Transport properties of the kesterite-like single crystals of Cu2ZnSnS4, Cu2ZnSnxGe1âxSe4 and Cu2ZnGeS4 are investigated in pulsed magnetic fields up to Bâ¯=â¯20â¯T. The Mott variable-range hopping (VRH) conduction is established by investigations of the resistivity, Ï (T), in all the materials mentioned above within broad temperature intervals of ÎTv4â¯â¼â¯50-150â¯K, 50-250â¯K and 100-200â¯K, respectively. In addition, the Shklovskii-Efros VRH conductivity below Tv2â¯â¼â¯3-4â¯K, the nearest-neighbour hopping (NNH) charge transfer between Tâ¯â¼â¯250-320â¯K and the conductivity by activation of holes on the mobility threshold at temperatures outside ÎTv4, respectively, are observed in these materials. In Cu2ZnSnS4, magnetoresistance (MR) contains only a positive contribution, connected mainly to a shrinkage of impurity wave functions by the magnetic field. At the same time, a negative contribution to MR, attributable to interference effects in VRH, is observed in Cu2ZnSnxGe1âxSe4 and, especially, in Cu2ZnGeS4. The joint analysis of the MR and Ï (T) data has yielded important electronic parameters of the materials. This includes widths of the acceptor band W and of the Coulomb gap Î, the NNH activation energy En, the localization radius a, the acceptor concentration NA and the density of the localized states at the Fermi level, g (μ). A dramatic increase of a in Cu2ZnSnS4 with decreasing T is observed, whereas in Cu2ZnSnxGe1âxSe4 all the parameter W, En, g (μ), a and NA are non-monotonic functions of x. Finally, in Cu2ZnGeS4 the Hall coefficient RH (T) is negative (despite of the p-type conduction), exhibiting the dependence close to that of Ï (T) in the Mott VRH interval.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Condensed Matter Physics
Authors
E. Lähderanta, K. Lisunov, M.A. Shakhov, M. Guc, E. Hajdeu-Chicarosh, S. Levcenko, I. Zakharchuk, E. Arushanov,