MBE GROWTH OF FERROMAGNETIC (MN,NI)AL THIN-FILMS ON ALAS GAAS/

We describe the coherent epitaxy of MnNiAl fenomagnetic thin films on AlAs/GaAs heterostructures using molecular beam epitaxy. The epitaxy h elps to stabilize the tau phase, which is known to be a metastable fer romagnetic phase with a tetragonal lattice. The easy axis of the ferro magnetic thin film is oriented perpendicular to the surface as a conse quence of the coherent epitaxy. The results of structural and magnetic analysis are given for thin MnxAl1-x films with 0.40 < x < 0.60. We h ave further assessed the change in structural and magnetic properties of the thin films when Ni is added as a substitution for Mn in Mn0.60- yNiyAl0.40, with 0 < y < 0.18. We find that coherent epitaxy is obtain ed over these wide compositional ranges and that the change in magneti c properties using various Ni additions adds a degree of freedom in th e design of ferromagnetic thin layers on AlAs/GaAs for future device s tructures.