Research Papers in Physics and Astronomy

 

Date of this Version

July 2004

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Published by American Physical Society. © 2004. Permission to use. Phys. Rev. B. 70, 014421 (2004)

Abstract

raining of the exchange bias effect in antiferro-/ferromagnetic heterostructures is considered in the theoretical framework of spin configurational relaxation, which is activated through consecutively cycled hysteresis loops. The corresponding exchange bias fields, µ0 HEB(n), reveal relaxation from the initial state, n = 1, of high antiferromagnetic interface magnetization to the equilibrium state of reduced magnetization in the limit of large n. The evolution of µ0HEB vs n is calculated with the help of a discretized Landau-Khalatnikov equation, where the continuous time parameter is replaced by the loop index n. The result reveals the origin of the well established but hitherto unexplained power-law decay of µ0HEB(n) for n > 1. Moreover, in contrast with the breakdown of the power-law behavior at n = 1, the relaxation approach describes the training effect for n≥1. The full capability of the theory is explored in comparison with experimental results obtained recently on a NiO(001)/Fe(110) heterostructure.

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