Low-temperature magnetoresistance in two-dimensional magnesium films

We have measured the low-temperature (0.1-10 K) magnetoresistance of thin two-dimensional films of magnesium. A crossover from positive to negative magnetoresistance is observed at low fields. This allows a unique determination of both the spin-orbit scattering length and the inelastic scattering length at each temperature. Below 0.2 K in the 22.3 $\frac{\Omega }{\square }$ magnesium film, we find that the inelastic diffusion length of the electron is greater than 1 $\mu$m.