Magnetostructural transition and large magnetocaloric effect in (Mn0.6Fe0.4)NiSi1-xAlx (x=0.06-0.08) alloys

First order coupled magnetostructural transition (MST) between ferromagnetic orthorhombic and paramagnetic hexagonal structure and large magnetocaloric effect are reported in the present article in transition metal based Al doped (Mn0.6Fe0.4)NiSi1-xAlx (x = 0.06, 0.07) alloys. On doping Al in place of Si, the structural transition temperature is found to shift to around room temperature (similar to 272 K for x = 0.07) from a high temperature of similar to 1210 K for MnNiSi system. On further increase in Al doping with x = 0.08, only magnetic transition is observed at similar to 145 K. Isothermal magnetic entropy change (Delta S-M) as large as similar to 20.6 Jkg(-1) K-1 is found for the alloy with x = 0.07 due to a change of 50 kOe magnetic field. Large value of Delta S-M observed near room temperature for the alloy with x = 0.07 enable it as a potential candidate for magnetic refrigerant.