Spontaneous exchange bias: Unidirectional anisotropy in an otherwise isotropic system

We propose a mechanism that is capable of inducing a unidirectional anisotropy in an otherwise isotropic ferromagnet-antiferromagnet system just by the mere application of the first field point in the hysteresis loop evaluation. The connection between this mechanism and the nonzero exchange bias obtained in a hard-axis hysteresis loop is also discussed. The system of Ni80 Fe20 Ni50 Mn50 has been simulated using a large-scale micromagnetic model to illustrate this effect.