Вид документа : Статья из журнала Шифр издания : 54/M 45 Автор(ы) : Laiho R., Lisunov K. G., Laehderanta E., Shakhov M. A., Stamov V. N., Zakhvalinskii V. S., Kozhevnikov V. L., Leonidov I. A., Mitberg E. B., Patrakeev M. V. Заглавие : Mechanisms of hopping conductivity in weakly doped La1-xBaxMnO3 Место публикации : Journal of Physics: Condensed Matter. - 2005. - Vol. 17, № 21. - С. 3429-3444 Примечания : Библиогр. : с. 3444 (35 назв.) ББК : 54 Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ Ключевые слова (''Своб.индексиров.''): керамика--манганиты Аннотация: The resistivity, ρ, of ceramic La1−xBaxMnO3 with x = 0.02–0.10 corresponding to the concentrations of holes c ≈ 0.15–0.17 displays an activated behaviour both above and below the paramagnetic to ferromagnetic transition temperature TC = 175–209 K, obtained from measurements of the magnetization. Above T~ 310–390 K ρ(T, x) is determined by nearest-neighbour hopping of small polarons with activation energy Ea = 0.20–0.22 eV. Below the onset temperature Tv = 250–280 K, depending on x, a Shklovskii–Efros-like variable-range hopping conductivity mechanism, governed by a soft temperature independent Coulomb gap, The resistivity, ρ, of ceramic La1−xBaxMnO3 with x = 0.02–0.10 corresponding to the concentrations of holes c ≈ 0.15–0.17 displays an activated behaviour both above and below the paramagnetic to ferromagnetic transition temperature TC = 175–209 K, obtained from measurements of the magnetization. Above T ~ 310–390 K ρ(T, x) is determined by nearest-neighbour hopping of small polarons with activation energy Ea = 0.20–0.22 eV. Below the onset temperature Tv = 250–280 K, depending on x, a Shklovskii–Efros-like variable-range hopping conductivity mechanism, governed by a soft temperature independent Coulomb gap, ≈ 0.44–0.46 eV, and a rigid gap, δ(T ), is found. For the range T ~ 50–120K, δ(T ) is connected to the formation of small lattice polarons in conditions of strong electron– phonon interaction and lattice disorder. The rigid gap obeys a law δ(T ) ~ T 1/2 within two temperature intervals above and below TC, exhibits an inflection at TC and reaches at Tv a value of δv ≈ 0.14–0.18 eV. Such behaviour suggests a spin dependent contribution to δ(T ). The localization radius of the charge carriers, a, has different constant values within the temperature intervals where δ(T ) ~ T 1/2. With further decrease of T , a increases according to the law expected for small lattice polarons ≈ 0.44–0.46 eV, and a rigid gap, δ(T ), is found. For the range T ~ 50–120K, δ(T ) is connected to the formation of small lattice polarons in conditions of strong electron– phonon interaction and lattice disorder. The rigid gap obeys a law δ(T ) ~ T 1/2 within two temperature intervals above and below TC, exhibits an inflection at TC and reaches at Tv a value of δv ≈ 0.14–0.18 eV. Such behaviour suggests a spin dependent contribution to δ(T ). The localization radius of the charge carriers, a, has different constant values within the temperature intervals where δ(T ) ~ T 1/2. With further decrease of T , a increases according to the law expected for small lattice polarons Держатели документа: Центральная научная библиотека УрО РАН Доп.точки доступа: Laiho, R.; Lisunov, K. G.; Laehderanta, E.; Shakhov, M. A.; Stamov, V. N.; Zakhvalinskii, V. S.; Kozhevnikov, V. L.; Кожевников Виктор Леонидович; Leonidov, I. A.; Леонидов Илья Аркадьевич; Mitberg, E. B.; Митберг Эдуард Борисович; Patrakeev, M. V.; Патракеев Михаил Валентинович