Negative Magnetoresistance in the Variable-Range-Hopping Transport of Strongly Underdoped La2−xSrxCuO4
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چکیده
The in-plane transport of strongly underdoped La2−xSrxCuO4 films was examined in the magnetic fields up to 14 T and in temperatures down to 1.6 K. While at high temperatures the samples display metallic-like resistivity, the low-T transport is governed by variable-range-hopping mechanism. Careful analysis shows that the temperature dependence of pre-exponential factor in Mott’s variable-range-hopping law may not be neglected and that the density of states at the Fermi level can be effectively expressed as g(E − EF) = N0(E − EF), with a small exponent p of the order of 0.1. In the magnetic field parallel to CuO2 planes one of the variable-range-hopping parameter, ρ0, increases by about 20–25%, while the other one, T0, decreases by about 10–15%, resulting in the decrease in total resistivity. This effect may be related to the decrease of the tunneling barrier between different antiferromagnetic clusters in the presence of magnetic field.
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تاریخ انتشار 2006