Abstract Ni–Mn-Ga(Co, Cu) alloys have implicated magnetoresistance mechanisms as ferromagnetic shape memory alloys. The relationship between magnetoresistance and the martensitic transformation was researched. The magnetoresistance mechanism of microwires was related to the reorientation of martensite induced by magnetic fields. It is found that a negative MR of 4.81% was obtained in 20 kOe field in Ni48Mn22Ga22Co4Cu4 microwires with diameters of 0.28 mm at 327 K. The effect of diameters on the martensitic transformation observed in ρ-T curves could be explained as the effect of rapid quenching during the preparation process, that smaller diameters wires have faster cooling rate and lower atomic order.

中文翻译：

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Ni48Mn22Ga22Co4Cu4微丝磁阻研究

摘要 Ni-Mn-Ga(Co, Cu) 合金具有作为铁磁形状记忆合金的磁阻机制。研究了磁阻与马氏体相变的关系。微丝的磁阻机制与磁场引起的马氏体重新取向有关。结果表明，在 327 K 时，直径为 0.28 mm 的 Ni48Mn22Ga22Co4Cu4 微丝在 20 kOe 场中获得 4.81% 的负 MR。直径对 ρ-T 曲线中观察到的马氏体转变的影响可以解释为快速在制备过程中淬火，较小直径的丝具有更快的冷却速度和更低的原子序。