Respective dependencies of conventional and spontaneous exchange biases on spin glass

A conventional exchange bias manifests itself as a hysteresis loop shift in systems with an interface between a ferromagnet and an antiferromagnet after field cooling. Due to the complicated magnetic interactions at the interface, a spin glass with disordered and frustrated spin configurations is generated, resulting in the dependencies of the conventional exchange bias mechanism on a spin glass still being elusive. Here, we report that a spin glass, CuMn, exhibits a conventional exchange bias as in interface magnetic systems. More importantly, a spontaneous exchange bias is also observed in the spin glass after zero-field cooling, which is attributed to the response of ferromagnetic clusters embedded in a spin-glass matrix at high magnetic fields that form a unidirectional anisotropy through the interaction between the clusters and the spin-glass matrix. Our results show the relationship between the exchange bias and spin glasses, offering a foundational understanding for exchange bias research.