On the order of magnetic transition in MnCo1−xFexGe (x = 0.20, 0.06 and 0.03) mechanical alloys

Mechanically amorphized MnCo1−xFexGe alloys (x = 0.20, 0.06 and 0.03) were used as precursors to obtain hexagonal austenite single phase samples. Combining thermomagnetic and magnetocaloric analysis and in situ X-ray diffraction, we observed that the presence of a distribution of transition temperatures jeopardizes the first order character of the magnetoelastic transition from the ferromagnetic to paramagnetic state. Both magnetothermal and in situ X-ray diffraction identify the presence of such distribution and the first order character of the magnetoelastic transition. •Mechanical alloying stabilizes austenite phase in MnCo1−xFexGe system.•Curie distribution jeopardizes first order character of magnetic transition.•Field exponent of magnetic entropy change agrees with first order character.•Conventional Banerjee criterion fails to describe first order character.•Magnetoelastic transition observed for x = 0.2 by in-situ cell volume changes.