Academic Journal
Variable-range hopping conductivity in La1-xCaxMnO3
| العنوان: | Variable-range hopping conductivity in La1-xCaxMnO3 |
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| المؤلفون: | Laiho, R., Лайхо, Р., Lisunov, C.G., Lisunov, K.G., Lahderanta, E.M., Stamov, V.N., Zakhvalinskii, V.S. |
| المصدر: | Journal of Physics Condensed Matter 1233-1246 |
| سنة النشر: | 2001 |
| مصطلحات موضوعية: | Engineering controlled terms Activation energy, Carrier concentration, Crystal lattices, Electric conductivity of solids, Electron transitions, ferromagnetism, magnetization, Paramagnetism, Polarons, Thermal effects, X ray diffraction analysis Engineering uncontrolled terms Coulomb gap, dielectric permeability, Lanthanum calcium manganate, Lattice polarons, Magnetic polarons, Variable range hopping conductivity Engineering main heading Lanthanum compounds |
| الوصف: | In ceramic La1-3CaxMnO3nbsp;samples with 0 le; x le; 0.15 and the concentration of holes c = 0.18-0.22 between T = 77 and 340 K the resistivity, rho;, is shown to have an activated character both above and below the ferromagnetic Curie temperature, TC. The temperature dependence of the local activation energy, Elocnbsp;T = d 1n rho;T/dkT-1nbsp;gives evidence for a variable-range hopping conductivity over states of the Coulomb gap. The width of the gap Delta; asymp; 0.24eV, the effective dielectric permeability kappa; asymp; 3.6 and the carrier localization radius xi; asymp; 5.1 angstrom in the paramagnetic phase are determined. The value of xi; suggests hopping of small lattice polarons at T TC. With decreasing temperature two successive transitions, at temperatures Tprime;Cnbsp;and TPrime;C, associated with divergence of the correlation length, are observed in the vicinity of TC. They can be interpreted in terms of critical increase as T approaches Tprime;Cnbsp;from higher temperatures and decrease when T shifts from TPrime;Cnbsp;towards lower temperatures of the radius of magnetic polarons, generated by a small fraction of the lattice polarons as T rarr; TC. The difference between TCnbsp;and the temperature of the first divergence of xi;, Tprime;Cnbsp; TC, gives evidence of percolative character of the FM-PM transition. |
| نوع الوثيقة: | article in journal/newspaper |
| وصف الملف: | application/pdf |
| اللغة: | English |
| تدمد: | 09538984 |
| Relation: | https://ibn.idsi.md/vizualizare_articol/198736; urn:issn:09538984 |
| DOI: | 10.1088/0953-8984/13/6/304 |
| الاتاحة: | https://ibn.idsi.md/vizualizare_articol/198736 https://doi.org/10.1088/0953-8984/13/6/304 |
| Rights: | info:eu-repo/semantics/openAccess |
| رقم الانضمام: | edsbas.2BE47A37 |
| قاعدة البيانات: | BASE |
| تدمد: | 09538984 |
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| DOI: | 10.1088/0953-8984/13/6/304 |