Transport properties of Co2CrAl Heusler alloy films

Abstract

The effect of atomic disorder on the electron transport and the magnetoresistance (MR) of Co2CrAl Heusler alloy (HA) films has been investigated. We show that Co2CrAl films with L2(1) order exhibit a negative value for the temperature coefficient of resistivity (TCR) in a temperature range of 10 < T < 290 K, and the temperature dependence of electric conductivity varies as T-3/2 similarly to that of the zero-gap semiconductors. The atomic or the site disorder on the way of L2(1) -> B2 -> A2 -> amorphous state in Co2CrAl HA films causes the deviation from this dependence: reduction in the absolute value of TCR as well as decrease in the resistivity down to rho(T = 293 K) similar to 200 mu Omega cm in comparison to rho(T = 293 K) similar to 230 mu Omega cm typical for the Co2CrAl films with L2(1) order. The magnetic-field dependence of MR of the Co2CrAl films with L2(1) order is determined by two competing contributions: a positive Lorentz scattering and a negative s-d scattering. The atomic disorder in Co2CrAl films drastically changes MR behavior due to its strong influence on the magnetic properties.