Heusler合金NiCoMnSn中的磁场驱动马氏体相变、超自旋玻璃和交换偏置

Magnetic field-induced martensitic transformation, superspin glass and exchange bias in Heusler alloys NiCoMnSn

合成了一系列Ni50-xCoxMn39Sn11(8≤x≤10)样品,并对它们的结构和磁性进行了研究.发现随Co含量的增加,样品的饱和磁化强度逐渐增强,并在Ni42Co8Mn39Sn11中实现了磁场诱发马氏体相变.另外,在Co大于8.0的成分中探测到了超自旋玻璃,并且观察到交换偏置现象.证实了超自旋玻璃的马氏体相和铁磁奥氏体母相共存,这也是产生交换偏置的原因.我们猜测超自旋玻璃的形成可能是来源于Mn-Mn团簇的存在,这和之前报道的Mn2Ni1.6Sn0.4的结果相一致[1].

The crystal structures and magnetic properties of Ni50-xCoxMn39Sn11 （8 ≤x≤10） Heusler alloys are investigated. As a result, we achieve the magnetic field induced martensitic transformation in Ni42Co8Mn39Sn11 . It is found that the saturation magnetic moments of alloys increase with Co content increasing. Moreover, a superspin glass behavior and a large exchange bias effect are also found in samples with Co content being higher than 8. We confirm the coexistence of superspin glass of the martensite and ferromagnetic parent phase, which is the physical origin of the exchange bias effect. On the other hand, we propose that the origin of superspin glass in our NiMnCoSn system is due to the occurence of Mn-Mn cluster as reported by Ma et al. in Heusler Mn2Ni1.6Sn0.4 alloys