Thickness dependence of weak localization in thin films of Ni/Cr alloy

In order to study the weak localization effect in thin films, Ni and Cr were simultaneously deposited using DC magnetron sputtering onto sapphire substrates at 573 K. These thin films ranged from $\approx$ 100 nm to 0.3 nm and contained $\approx$80/20 Ni/Cr by weight. The samples were then cooled from room temperature to $\approx$ 6 K in order to measure the sheet resistance (measured using the standard Van der Pauw technique) vs. the temperature of the sample. Normal metalic behavior during cool down is observed in thicker films. However, the films exhibitted a metal-insulator transition at a particular tempurature which increased as film thickness was decreased. This transition can be attributed to the electrons becoming weakly localizing as different scattering behaviors begin to dominate.