Transport at low temperature in amorphous magnetic metals (invited)

The scaling theory of conduction for a noninteracting electron gas in a disordered system at T = 0 is reviewed and the conductivity at various length scales obtained. The concepts of the mean free time between inelastic collisions and the corresponding inelastic length lin, are introduced. The conductivity for a dirty metal is obtained as a function of temperature at low temperatures in terms of lin(T). For the case of a disordered magnetic metal the effect of the temperature-dependent magnetic disorder is introduced and several possible typical situations schematically analyzed. The effect of electron-electron interactions is briefly discussed, as determining the effective inelastic length and a simple qualitative picture of conduction as a function of temperature suggested. Some cautionary remarks about the testing of these ideas by experiments are made.