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SM ISO690:2012 LAIHO, Reino, LISUNOV, Konstantin, LÄHDERANTA, Erkki, SHAKHOV, Mikhail, STAMOV, Vladimir, ZAKHVALINSKII, Vasilii, KOZHEVNIKOV, Vladimir, LEONIDOV, Ilia, MITBERG, Eduard, PATRAKEEV, Mikhail. Mechanisms of hopping conductivity in weakly doped La1-xBa xMnO3. In: Journal of Physics Condensed Matter, 2005, vol. 17, pp. 3429-3444. ISSN 0953-8984. DOI: https://doi.org/10.1088/0953-8984/17/21/033 |
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Journal of Physics Condensed Matter | |
Volumul 17 / 2005 / ISSN 0953-8984 /ISSNe 1361-648X | |
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DOI:https://doi.org/10.1088/0953-8984/17/21/033 | |
Pag. 3429-3444 | |
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Rezumat | |
The resistivity, ρ, of ceramic La1-xBaxMnO 3 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 T C = 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 E a = 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, Δ≈0.44-0.46 eV, and a rigid gap, δ(T), is found. For the range T∼50-120 K, 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)∼T1/2 within two temperature intervals above and below TC, exhibits an inflection at TC and reaches at T v 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)∼T1/2. With further decrease of T, a increases according to the law expected for small lattice polarons. |
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Cuvinte-cheie Engineering controlled terms Activation energy, Ceramic materials, Colossal magnetoresistance, ferromagnetism, Lanthanum compounds, magnetization, Manganese compounds, Paramagnetism, perovskite, Polarons Engineering uncontrolled terms Electron-phonon interactions, Hopping conductivity, Lattice disorder, Lattice polarons Engineering main heading Electric conductivity |
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