First-order magnetostructural transformation in Fe doped Mn–Co–Ge alloys

Abstract

• We have achieved FOMT by substituting Mn by Fe atoms in off-stoichiometric MnCoGe. • A giant MCE (△ S m = −9.74 J kg −1 K −1 at △ H = 0–5 T for Mn 0.89 Fe 0.11 CoGe) was obtained. • Large lattice strain up to ∼12% accompanied by the transformation was observed. Substitution of Fe for Mn atoms in Mn–Co–Ge alloys was employed for tailoring concurrent structural and magnetic phase transitions. First-order magnetostructural transition from paramagnetic hexagonal Ni 2 In-type parent phase to ferromagnetic orthorhombic TiNiSi-type martensite was achieved. A giant magnetocaloric effect of △ S m = −9.74 J kg −1 K −1 was obtained under magnetic field change of 5 T in the vicinity of phase transition temperature. This result indicates that Fe doped Mn–Co–Ge alloys are ideal candidates for magnetic refrigeration applications. Furthermore, the magnetic field-induced martensitic transformation, associated with a large lattice strain of ∼12%, was directly evidenced by in situ synchrotron high-energy X-ray diffraction.