INTERPLAY BETWEEN BIQUADRATIC COUPLING AND THE NEEL TRANSITION IN FE CR94FE6(001) SUPERLATTICES/

The commensurate antiferromagnetic order of Cr94Fe6 alloy layers in ep itaxial Fe/Cr94Fe6(001) superlattices was investigated by transport an d magnetization techniques. Neel temperature T-N values are strongly t hickness dependent, with T-N suppressed for Cr94Fe6 thicknesses < 36 A ngstrom. Transport results indicate a broadening of the transition wit h an onset temperature T-0 > T-N by approximate to 150 K for all sampl es. The biquadratic Interlayer coupling of the Fe layers is enhanced f or T-N < T < T-0 and suppressed below T-N. T-0 and T-N are identified with the onset on cooling of inhomogeneous and homogeneous order, resp ectively, within the spacer layers. The regime of inhomogeneous orderi ng of the spacer is believed to promote biquadratic coupling because o f the dominance of interfacial exchange energies.