Training of the exchange-bias effect: A simple analytic approach

Authors

Christian Binek, University of Nebraska-LincolnFollow

Date of this Version

July 2004

Comments

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 H_EB(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 µ₀H_EB 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 µ₀H_EB(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.