Enhanced room temperature exchange bias caused by antiferromagnetism strengthening

In this work, Mn₅₅Bi_45-xB_x (0 ≤ x ≤ 2) alloys were prepared by arc-melting, and the low-temperature ferromagnetic MnBi phase was investigated in 300 K. Through the XRD refinement results, it can be found that the lattice parameters of the alloys change with the B doping amount. When x = 1, an optimal room temperature spontaneous exchange bias effect was observed in the Mn₅₅Bi₄₄B. This phenomenon can be attributed to B with a smaller atomic radius occupying the Bi position, resulting in more Mn atoms into interstitial sites and more antiferromagnetic clusters on the ferromagnetic matrix. This work focuses on the effect of B doping on the structure and exchange bias behavior in Mn₅₅Bi₄₅ alloy, providing a way to design room temperature spintronic devices.