A freezing ferromagnetic moment model for exchange bias in α-fe ₂o₃ nanoleaves

We propose a freezing ferromagnetic moment model to explain the exchange bias discovered in α-Fe₂O₃ antiferromagnetic nanoleaves most recently. The model assumes that in the antiferromagnetic nanosystem, the disorder surface spins are frozen at low temperature along magnetic filed direction, forming a ferromagnetic layer. Then this frozen ferromagnetic surface state couples with the inside antiferromagnetic layers that results in an exchange bias. After some proper simplification, we get the magnetization at different applied field by the minimal energy calculation using MATLAB. Our model computerizing indicates the exchange bias shift of the magnetization curve is -48.2 Oe for n = 100 antiferromagnetic layers, which matches the observed value very well.