Positive Exchange Bias in Fe<span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">F</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math></span>-Fe Bilayers

J. Nogués; D. Lederman; T. J. Moran; Ivan K. Schuller

doi:10.1103/PhysRevLett.76.4624

Positive Exchange Bias in Fe $F_{2}$ -Fe Bilayers

J. Nogués, D. Lederman, T. J. Moran, and Ivan K. Schuller

Phys. Rev. Lett. 76, 4624 – Published 10 June 1996

Abstract

We have discovered a positive unidirectional exchange anisotropy in antiferromagnetic (Fe $F_{2}$ ) and ferromagnetic (Fe) bilayers cooled through the antiferromagnetic critical temperature $T_{N}$ in large magnetic fields. For low positive cooling fields, the ferromagnet's magnetization ( $M - H$ ) loop center shifts to negative fields, as is normally observed in other systems. In contrast, large cooling fields can cause the shift to be positive. This can be explained if the Fe $F_{2}$ surface spins couple to the external magnetic cooling field above $T_{N}$ and the Fe $F_{2}$ -Fe interaction is antiferromagnetic.

Received 23 February 1996

DOI:https://doi.org/10.1103/PhysRevLett.76.4624

Authors & Affiliations

J. Nogués¹, D. Lederman², T. J. Moran¹, and Ivan K. Schuller¹

¹Physics Department 0319, University of California at San Diego, La Jolla, California 92093-0319
²Physics Department, West Virginia University, Morgantown, West Virginia 26506-6315