Variable range hopping and spin-dependent hopping resistance in magnetic iron oxide films

摘要

Insulating iron oxide films exhibit variable-range-hopping conductance. From 100 K to near room temperature the resistance can be expressed as R = R-0 exp(T-0/T)(P), where p takes values of 0.6-0.7. p is unchanged in an applied field up to 9 T. The magnetoresistance of the films is negative, which increases in magnitude with decreasing temperature. The negative magnetoresistance may originate from the spin-dependent variable-range-hopping in which hopping rate depends on the relative orientation of the spins of the involved sites. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 13]