Single crystal Heusler alloy Ni2MnAl thin films have been grown by molecular beam epitaxy on GaAs (0 0 1) using Sc0.3Er0.7As interlayers. The effect of growth temperature on the structural and magnetic properties was studied. Films grown at lower temperatures were non-ferromagnetic with a B2-like crystal structure; while higher growth temperature (400degreesC) resulted in ferromagnetic films suggesting a L2(1)-like structure. Exchange bias was detected in Ni2MnAl/Ni2MnGe (ferromagnetic) and Co/Ni2MnAl bilayers, suggesting that the Ni2MnAl films grown at 180degreesC (in the B2-like structure) are anti ferromagnetically ordered. (C) 2003 Elsevier Science B.V. All rights reserved.