Strong magneto-volume effects and hysteresis reduction in the In-doped (NiCo)2MnGa Heusler alloys

• Samples of Co and In doped Ni2MnGa based alloys with transitions near room temperature.
• Significant decrease of magnetization induced by pressure, dlnMM(5 K)/dP = −55 × 10−3 GPa−1.
• Reduction of more than 25 K of the hysteresis of the structural transition by external pressure.

We report the effect of high hydrostatic pressure (up to 1.1 GPa) on magnetization and critical temperatures of the magnetic and magneto-structural transitions in the off-stoichiometric In-doped (Ni,Co)2Mn(Ga,In) alloys. The magnetization MM(5 K) of their martensitic phase significantly decreases under pressure and the value of dlnMM(5 K)/dP = −55 × 10−3 GPa−1 was observed in the Ni41Co9Mn33Ga14In3 alloy. The temperature of structural transition of the alloys from martensite to austenite, TM-A, shows a strong dependence on both pressure (dTM-A/dP = 60 K/GPa) and magnetic field. The complex mutual dependence of TM-A to both pressure and magnetic field produces a remarkable reduction of the transformation hysteresis.

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