Enhancement of diamagnetic susceptibility in amorphous semiconductors

Abstract

We have used a localized bond-orbital model to calculate the magnetic susceptibility x of a model elemental semiconductor in the amorphous phase. The amorphous state has been approximated by disorder in the bond angles only; the bond lenghts have been assumed to be unchanged from their crystalline values. To calculate x dia and x para, the dia- and paramagnetic parts of x associated with the valence band electrons, a representation in which the bond-orbitals orbitals at each site are orthogonal, is used. We find that in going from the crystalline to the amorphous phase; (i) the magnitude of x dia does not always increase which is in contrast to some earlier theoretical results and; (ii) x para is reduced if a certain average energy denominator increases or remains unchanged. We argue that for Ge and Si, the diamagnetic enhancement in going from the crystalline to the amorphous phase is likely to be large as seen experimentally.