| Autor: |
Usatyy, I. M., Zakhvalinskii, V. S., Ivanov, O. N., Ivanichikhin, S. V., Morocho, A. A. |
| Předmět: |
|
| Zdroj: |
Ferroelectrics; 2020, Vol. 561 Issue 1, p12-22, 11p |
| Abstrakt: |
The temperature dependences of the resistivity ρ(T) of ceramic La 1 − x Sr x Mn 1 − y Fe y O 3 samples at x = 0.5, and y = 0, 0.02 and 0.10 are investigated in the temperature range of 5-300 K in magnetic field B up to 1 T. It was found that dependences ρ(T) with x = 0.5; y = 0.02, and 0.10 obey the Shklovskii–Efros-like variable-range hopping conductivity law ρ (T) = ρ 0 (T) exp [ (T 0 / T) 1 / 2 ]. This behavior is governed by generation of a soft Coulomb gap Δ ≈ 0.3 eV in the density of localized states, as well as a rigid gap δ v ≈ 0.20 and 0.17 eV at y = 0.02 and y = 0.10, respectively. The obtained values of the rigid gap at y = 0.02 indicate the presence of charge ordering. It was shown that a decrease in the width of the rigid gap when y is increased, is accompanied by both a growing disorder attributed to the presence of Fe and a decrease in lattice distortions caused by charge ordering at y = 0.02. It is shown that the pre-exponential factor of resistivity follows the law ρ 0 (T) ∝ T m , where m changes from 9/2 at y = 0.02 to 5/2 at y = 0.10. This confirms that doping with Fe enhances microscopic disorder by introducing an additional fluctuating short-range potential. The calculated values of the carrier localization radius α ≈ 5.1 and 2.7 Å at y = 0.02 and y = 0.10, respectively, satisfy the condition for the formation of small polarons. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
