Variable-range hopping conduction in LaMnO3 + δ

被引：0
作者：
V. S. Zakhvalinskiĭ
R. Laiho
K. G. Lisunov
E. Lähderanta
P. A. Petrenko
Yu. P. Stepanov
V. N. Stamov
M. L. Shubnikov
A. V. Khokhulin
机构：
[1] Belgorod State University,Wihuri Physical Laboratory
[2] University of Turku,Institute of Applied Physics
[3] Academy of Sciences of Moldova,Department of Physics
[4] Lappeenranta University of Technology,Ioffe Physicotechnical Institute
[5] Russian Academy of Sciences,undefined
来源：
Physics of the Solid State | 2007年 / 49卷
关键词：
75.47.Lx; 74.25.Fy; 74.62.Dh; 75.47.Gk; 75.30.Et;
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摘要：
The temperature dependence of the electrical resistivity ρ(T) for ceramic samples of LaMnO3 + δ (δ = 0.100–0.154) are studied in the temperature range T = 15–350 K, in magnetic fields of 0–10 T, and under hydrostatic pressures P of up to 11 kbar. It is shown that, above the ferromagnet-paramagnet transition temperature of LaMnO3 + δ, the dependence ρ(T) of this compound obeys the Shklovskii-Efros variable-range hopping conduction: ρ(T) = ρ0(T)exp[(T0/T)1/2], where ρ0(T) = AT9/2 (A is a constant). The density of localized states g(ɛ) near the Fermi level is found to have a Coulomb gap Δ and a rigid gap γ(T). The Coulomb gap Δ assumes values of 0.43, 0.46, and 0.48 eV, and the rigid gap satisfies the relationship γ(T) ≈ γ(Tv)(T/Tv)1/2, where Tv is the temperature of the onset of variable-range hopping conduction and γ(Tv) = 0.13, 0.16, and 0.17 eV for δ = 0.100, 0.125, and 0.154, respectively. The carrier localization lengths a = 1.7, 1.4, and 1.2 Å are determined for the same values of δ. The effect of hydrostatic pressure on the variable-range hopping conduction in LaMnO3 + δ with δ = 0.154 is analyzed, and the dependences Δ(P) and γv(P) are obtained.
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页码：918 / 924
页数：6
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