Weak localisation and interaction effects in amorphous CuTi alloys

Abstract

The electrical resistivity of amorphous Cu60Ti40 and Cu65Ti35 has been measured at temperatures between 20 mK and 18 K and in magnetic fields up to 4 T. The results are discussed in a framework given by the weak localisation theory including spin-orbit scattering and spin splitting (Fukuyama and Hoshino in 1981 (FH)) and electron-electron interaction theories (Al'tshulet et al. in 1984 (AA), Lee and Ramakrishnan in 1985). Values for the inelastic and spin-orbit scattering lifetimes are derived from the magnetic field dependence of the resistivity, rho (B). Independent determinations from the temperature dependence of rho give qualitative results in agreement with these values. The large spin-orbit scattering time in this alloy system makes a more accurate analysis of rho (T) difficult. The strong dependence on the diffusion constant in the results from rho (B) below 1 K is pointed out. Important differences between the FH and AA formulations of the weak localisation theory are stressed. In particular, the observed temperature dependence of rho (B) in the region where it is linear in square root B can be explained only within the FH theory.