First-order antiferromagnetic to ferromagnetic transition in Mn(Co,Fe)P probed by x-ray absorption experiments

The first-order antiferromagnetic to ferromagnetic transition taking place near to room temperature in MnCo0.53Fe0.47P has been investigated by x-ray absorption techniques: in the near edge region (XANES), in the extended energy range (EXAFS) and by using magnetic circular dichroism (XMCD). The absence of significant changes in the electronic and crystal structures across the transition are at odds with recent results obtained for the first-order magnetic transitions of the closely related Mn alloys, MnFe(P, Si, B) and MnCoGe. This points out that the microscopic mechanism responsible for the discontinuous antiferromagnetic to ferromagnetic transition in the Mn(Co, Fe) P system is intrinsically different from these latter prototypical examples.