Magnetic Materials Laboratory, Department of Physics, Indian Institute of Technology Bombay, Mumbai-400076, India.
J Phys Condens Matter. 2011 Oct 19;23(41):416004. doi: 10.1088/0953-8984/23/41/416004. Epub 2011 Sep 28.
We have performed ac susceptibility and dc magnetization measurements in Ni(50-x)Co(x)Mn(38)Sb(12) Heusler alloys. From the ac susceptibility measurements, the existence of reentrant spin glass (RSG) state is observed for x=0-5. It is found that the signature of RSG behavior diminishes with increase in x. This behavior is in contrast to the fact that the exchange bias field increases with x, which reveals that the origins of RSG and exchange bias are different in the present system. It is found that the system enters a frustrated ferromagnetic state just below the Curie temperature of the martensite phase (T(M)(C)) and then the RSG state at low temperature. The strength of the RSG state is critically dependent on the sharpness of the magnetic transition at (T(M)(C)). This proposition is further supported by the thermo-remanent magnetization and low field thermomagnetic measurements.
我们在 Ni(50-x)Co(x)Mn(38)Sb(12) Heusler 合金中进行了交流磁化率和直流磁化测量。从交流磁化率测量中，观察到 x=0-5 时存在反铁磁自旋玻璃 (RSG) 态。发现随着 x 的增加，RSG 行为的特征减弱。这种行为与交换偏置场随 x 增加的事实形成对比，表明在当前体系中，RSG 和交换偏置的起源不同。发现该系统在马氏体相居里温度 (T(M)(C)) 以下进入受挫折铁磁状态，然后在低温下进入 RSG 状态。RSG 状态的强度与 (T(M)(C)) 处的磁转变的锐度密切相关。这一观点得到了热剩磁和低场热磁测量的进一步支持。
