Correlation effect on hopping conduction in a magnetic field

Both the correlation effect and the interference effect are taken into account in hopping conduction in the strongly Anderson-localized regime. A new mechanism for the positive magnetoconductance is suggested: the Zeeman effect increases the number of high-spin states, in which the orbitals at the Fermi level are more extended than in the low-spin states owing to the weaker short-range correlation effect. The magnetoconductance is independent of the direction of the magnetic field and can be observed in nearest-neighbor hopping conduction.