Suppression of biquadratic coupling at the Cr Néel temperature in Fe/Cr(001) superlattices (invited) (abstract)

Authors

Eric E. Fullerton, Argonne National Laboratory
Shireen Adenwalla, University of Nebraska-LincolnFollow
G. Felcher, Argonne National Laboratory
C. H. Sowers, Argonne National Laboratory
S. D. Bader, Argonne National Laboratory
J. L. Robertson, Oak Ridge National Laboratory
A. Berger, University of California at Irvine

Date of this Version

1996

Citation

J. Appl. Phys. 79 (8), 15 April 1996

Comments

© 1996 American Institute of Physics

Abstract

We present the effects of antiferromagnetic (AF) order of the Cr spacers in Fe/Cr(001) superlattices on the interlayer coupling of the Fe layers. AF order of the Cr spacers is suppressed for layer thicknesses less than 42 Å. For .42 Å of Cr, the Néel temperature (T_N) increases rapidly and asymptotically approaches the bulk value for thick Cr spacers as characterized by a transition-temperature shift exponent λ=1.4 ±0.3. Neutron diffraction confirms both the AF order of the Cr layers in superlattices with 62, 100, and 200 Å thick Cr layers, and the existence of the incommensurate, transverse spin-density-wave magnetic structure whose nesting wave vector is equal to that of bulk Cr. The AF ordering of the Cr results in anomalies in a variety of magnetic properties, including the interlayer coupling, remanent magnetization, coercivity, and magnetoresistance. Most strikingly, the 90° or ‘‘biquadratic’’ coupling of the Fe layers observed for T>T_N is suppressed below T_N as confirmed by polarized neutron reflectivity. This behavior can be understood in terms of the combination of finite-size and spin frustration effects at rough Fe/Cr interfaces.