Properties of Heusler alloy Co$_{2}$Cr$_{1-x}$Fe$_{x}$Al epitaxial thin films

We have studied properties of thin films of the new compound Heusler alloy Co$_{2}$Cr$_{1-x}$Fe$_{x}$Al. Recently, calculations have shown ordered compounds with small amounts of Fe doping to be half-metallic, and a magnetoresistance of approximately 30{\%} has been measured in bulk polycrystalline samples by others. Using physical vapor deposition, we have grown Co$_{2}$Cr$_{1-x}$Fe$_{x}$Al epitaxially on MgO. Our results show that the films are highly disordered and have a reduced magnetization as compared to the bulk and to theoretical predictions. Studies of films incorporated into current in plane spin valves show relatively large giant magnetoresistances, especially for a Heusler alloy. Recent results also indicate the presence of a large spin orbit coupling, which is unusual for a transition metal system.