Giant baroresistance effect with no hysteresis loss realized by a non-spontaneous martensitic transformation in Ni43Co7Mn35In15 alloy

Abstract

In this work, a non-spontaneous martensitic transformation (MT) activated by the hydrostatic pressure has been observed in polycrystalline Ni 43 Co 7 Mn 35 In 15 Heusler alloy. This alloy can experience a nearly complete metamagnetic MT with the assistance of an enough pressure. As the change of pressure reaches 20 kbar, the maximum baroresistance (BR) of the studied alloy achieves * 825% at 50 K and remains * 280% even in the vicinity of room temperature revealing a giant BR effect over a wide temperature range. More interestingly, the perfectly reversible isothermal BR effects as high as over 650% have been also found at the temperatures below 130 K by overcoming a thermal barrier between direct and reverse MTs. Such an interesting behavior could be ascribed to a pressureinduced continuous first-order MT accompanied by a prominent change of spin ordering, which brings about a combined contribution of electron-spin and electron-lattice scatterings.

Effect of Cu Doping on Phase Transition, Thermal Strain, and Thermal Expansion Property in Polycrystalline Ni50Mn23−xCuxGa27 Alloys

“…Besides, a cubic austenite phase with the highly ordered L 2 1 ‐type crystal structure appears in x = 1, 3, and 5 samples, which agrees with that reported in Ni 50 Mn 25 Ga 25 [ 32 ] and Ni 48 Fe 2 Mn 35 In 15 . [ 33 ] For samples with x = 6 and 7, all Bragg peaks can be indexed with a tetragonal martensitic structure, [ 34,35 ] suggesting their MT temperatures above room temperature. It is found that with increasing Cu element the room‐temperature structure changes from cubic structure to tetragonal structure.…”