Improved Wide-Temperature-Range Magnetocaloric Properties of (Mn,Fe)2(P,Si) Alloys by Mg-Co Co-Doping

To enhance the wide-temperature-range magnetocaloric performance of (Mn,Fe)2(P,Si) alloys, the effects of Mg-Co co-doping on their structural and magnetocaloric properties were systematically investigated. Mn1.05−yCoyFe0.9P0.5Si0.48Mg0.02 alloys were prepared by the arc melting method. The results show that Mg-Co co-doping can tune the lattice parameters and ferromagnetic coupling between Mn and Fe atoms. The Mn1.03Co0.02Fe0.9P0.5Si0.48Mg0.02 alloy exhibited an effective refrigeration capacity of 425.4 J·kg−1 and an effective working temperature span of 52 K. During the temperature-induced ferromagnetic transition, coupling between the magnetic moment of Fe-Si layers and the crystal lattice drives a magnetoelastic transition, leading to a giant magnetocaloric effect. The Mg-Co co-doping strategy effectively tunes the crystal structure and local electron density distribution of the Fe-Si layer, thereby influencing the total magnetic moment and magnetothermal properties of the alloys.