OSCILLATORY INTERLAYER COUPLING AND GIANT MAGNETORESISTANCE IN EPITAXIAL FE/CR(211) AND (100) SUPERLATTICES

An epitaxial orientation of Fe/Cr superlattices-Fe/Cr(211) on MgO(110)-is grown by magnetron sputtering. Its structural and magnetic characterizations are presented and compared to those for Fe/Cr(100) superlattices grown simultaneously onto MgO(100) substrates. The epitaxial orientation of the Fe/Cr(211) superlattices is Fe/Cr[011BAR] parallel-to MgO[001] and Fe/Cr[111BAR] parallel-to MgO[110BAR], while that for Fe/Cr(100) is Fe/Cr[00I] parallel-to MgO[0ll]. A uniaxial, in-plane surface anisotropy for the Fe/Cr(211) superlattices along the Fe[011BAR] of 0.06 erg/cm2 is obtained from analysis of the magnetization hysteresis loops. Four oscillations in the antiferromagnetic interlayer coupling and giant magnetoresistance (GMR) are observed with a period of 18 angstrom for both orientations. The strength, oscillation period, and phase of the magnetic coupling are identical for the two orientations. The GMR values increase by a factor of approximately 4 to 5 on cooling from room temperature to 4.2 K. At 4.2 K the maximum GMR value of the [Fe(14 angstrom)/Cr(8 angstrom)]50 superlattice is 70% for the (211) orientation and 150% for the (100) orientation.