High-field hopping magnetotransport in kesterites
| Autor: | Erkki Lähderanta, K. G. Lisunov, Sergiu Levcenko, Ernest Arushanov, M. A. Shakhov, I. Zakharchuk, Maxim Guc, E. Hajdeu-Chicarosh |
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| Rok vydání: | 2018 |
| Předmět: |
010302 applied physics
Materials science Condensed matter physics Magnetoresistance Fermi level 02 engineering and technology Conductivity 021001 nanoscience & nanotechnology Condensed Matter Physics Thermal conduction 01 natural sciences Acceptor Electronic Optical and Magnetic Materials Magnetic field symbols.namesake Electrical resistivity and conductivity Hall effect 0103 physical sciences symbols 0210 nano-technology |
| Zdroj: | Journal of Magnetism and Magnetic Materials. 459:246-251 |
| ISSN: | 0304-8853 |
| DOI: | 10.1016/j.jmmm.2017.10.094 |
| Popis: | Transport properties of the kesterite-like single crystals of Cu2ZnSnS4, Cu2ZnSnxGe1−xSe4 and Cu2ZnGeS4 are investigated in pulsed magnetic fields up to B = 20 T. The Mott variable-range hopping (VRH) conduction is established by investigations of the resistivity, ρ (T), in all the materials mentioned above within broad temperature intervals of ΔTv4 ∼ 50–150 K, 50–250 K and 100–200 K, respectively. In addition, the Shklovskii-Efros VRH conductivity below Tv2 ∼ 3–4 K, the nearest-neighbour hopping (NNH) charge transfer between T ∼ 250–320 K and the conductivity by activation of holes on the mobility threshold at temperatures outside ΔTv4, 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 Cu2ZnSnxGe1−xSe4 and, especially, in Cu2ZnGeS4. The joint analysis of the MR and ρ (T) data has yielded important electronic parameters of the materials. This includes widths of the acceptor band W and of the Coulomb gap Δ, 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 Cu2ZnSnxGe1−xSe4 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 ρ (T) in the Mott VRH interval. |
| Databáze: | OpenAIRE |
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