Twin-variant reorientation-induced large magnetoresistance effect in Ni₅₀Mn₂₉Ga₂₁single crystal

We report a significant magnetoresistance (MR) effect arisen from magnetic field-induced reorientation of martensitic twin variants in a ferromagnetic shape memory Ni50Mn29Ga21single crystal. The measured electrical resistivity shows large anisotropy and the measured MR value is as large as 25% over the wide temperature range of 230-315 K at a moderate magnetic field of 1.2 T. It is found that a proper combination of the initial state of martensitic twin variants and the direction and magnitude of applied magnetic field can give rise to either positive or negative MR value of ∼25%, thus allowing a periodic modulation of the MR effect in response to varying the spatial angle between the directions of applied magnetic field and electric current for every 180°.