Study of the temperature dependence of coercivity in MnBi

摘要

Two set of polycrystalline MnBi bulk samples, as-annealed and compacted powders, with different grain size, were prepared through powder metallurgy. Coercivity mechanisms were investigated by Kronmüller plot analysis, evaluating a and N_(eff) parameters, which take into account the effect of microstructure. The temperature dependence of coercivity of the as-annealed sample (a=0.31) is compatible with pinning-type mechanisms, while that of the compacted powders (a=0.41) indicates nucleation-type processes. Irreversible effects of temperature dependence of coercivity have been investigated.