TEMPERATURE-DEPENDENT STUDY OF ION-CHANNELING IN FE CR SUPERLATTICES/

Giant-Magneto-Resistance (GMR), as large as 150% at 4 K, occurs in Fe/ Cr superlattices as a result of antiferromagnetic interlayer coupling. We have successfully grown epitaxial single-crystal Fe/Cr multilayers using magnetron sputtering, Ion channeling was employed to study the structural and vibrational properties of the sputter-deposited Fe/Cr s uperlattices, and of a Cr thin film, between temperatures of 100 and 3 30 K. Channeling in the latter specimen was used to investigate the im portance of depositing a Cr-buffer layer in order to obtain superlatti ces with large GMR values. Once the buffer layer exceeded a critical t hickness, a high quality Cr film was observed, The epitaxial quality o f the superlattices grown on such buffer layers by sputtering was foun d to be excellent. Minimum yields nearly equal to theoretical predicti ons were found for channeling along the [001] growth direction; slight ly higher values were found along the [111] axis, Because of the high structural quality of the sputter-deposited films, it was possible to investigate changes in thermal vibration amplitudes, even though their magnitude is only of the order of a few pm (10(-12) m), No unusual st ructural changes of this magnitude were observed in angular channeling scans obtained while cooling the Fe/Cr superlattice from 330 down to 100 K.