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Variable-Range Hopping in the Array of Magnetic Quantum Dots

Published online by Cambridge University Press:  17 March 2011

M. Foygel ,
R. D. Morris  and
A. G. Petukhov
M. Foygel
Affiliation:
Physics Department, South Dakota School of Mines and Technology, Rapid City, SD 57701-3995
R. D. Morris
Affiliation:
USRA/RIACS, NASA Ames Research Center, Moffet Field, CA 94035-1000
A. G. Petukhov
Affiliation:
USRA/RIACS, NASA Ames Research Center, Moffet Field, CA 94035-1000
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Abstract

We analyzed the spin-dependent conductivity in the system of paramagnetic quantum dots embedded in semi-insulating matrix, which is due to bound magnetic polaron (BMP) inter-dot hopping. If such a system is characterized by wide distributions of the “bare” electron energies and BMP shifts, variable-range and variable-polaron-barrier hopping can be observed at low temperaturesT. It results in the giant magnetoresistance,ρ(H, T ) governed by a non-activation law, lnρ /α [T0(H)/T ]p, whereT0(H) drops with magnetic field,H. Depending on the conditions, parameters of the material, and the dimensionality of the system, the exponent 0.25 < p < 0.75. This type ofT -dependence has been observed in GaMnAs and MnGe magnetic semiconductors.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 690: Symposium F – Spintronics , 2001 , F10.7
Copyright
Copyright © Materials Research Society 2002

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References

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