Multiple magnetic transitions and associated room temperature magneto-functionality in Ni_2.048Mn_1.312In_0.64

Present work reports on the observation of multiple magnetic transitions in a Ni-excess ferromagnetic shape memory alloy with nominal composition Ni_2.048Mn_1.312In_0.64. The magnetization data reveal two distinct thermal hystereses associated with two different phase transitions at different temperature regions. The high temperature magnetic hysteresis is due to the martensitic phase transition whereas the low temperature hysteresis occurs around the magnetic anomaly signifying the transition from a paramagnetic-like state to the ferromagnetic ground state within the martensite. Clear thermal hysteresis along with the sign of the curvatures of Arrott plot curves confirm the first-order nature of both the transitions. In addition, the studied alloy is found to be functionally rich with the observation of large magnetoresistance (−45% and −4% at 80 kOe) and magnetocaloric effect (+16.7 J kg⁻¹ K⁻¹ and −2.25 J kg⁻¹ K⁻¹ at 50 kOe) around these two hysteresis regions (300 K and 195 K respectively). - Highlights: • Large magnetocaloric effect and magnetoresistance at room temperature. • Multiple magnetic and structural transitions. • First-order nature of the ferromagnetic transition in the martensite.