INTRASTATE AND INTERSTATE INTERACTIONS IN ANDERSON-LOCALIZED STATES

In order to investigate the interplay of randomness and electron correlation in the Anderson-localised states, a general theoretical model which treats the electron-electron interaction between these states is presented. In constructing the model Hamiltonian, the behaviour of localised states with envelope functions is explicitly taken into account. The spin susceptibility and electronic specific heat as well as the density of states are calculated for this model. It is shown that the intrastate correlation gives rise to the occurrence of singly occupied states below the Fermi energy EF and that this results in a Curie-type susceptibility at low temperatures. As a consequence of the variation in the correlation energy from state to state, the density of doubly occupied states becomes large near EF. It is also shown that the interactions between different localised states give rise to a kinetic exchange interaction between singly occupied states.