Large Coercivity and Novel Ultra-Sharp Magnetization in Sm(Ni0.5fe0.4al0.1)5

Abstract

In this study, the novel magnetization behavior at low temperature in rare-earth transition-metal intermetallic compound Sm(Ni0.5Fe0.4Al0.1)5 has been investigated, and large coercivity of 55 kOe and ultra-sharp step-like magnetization have been observed. The magnetization curve is smooth and the coercivity (Hc) increases exponentially with decreasing temperature when T>4.1 K. Thermal activation (TA) mechanism has been used to explain this behavior and based on the TA mechanism an energy barrier of about 0.46×10-21 J has been obtained. At T<4.1 K, sharp magnetization step appears and the coercivity Hc decreases with decreasing the temperature and tends to be constant at T<2.5 K. The ultra-sharp magnetization is explained as an avalanche magnetization process launched by an instantaneous domain wall motion. Significant increase in sample temperature has been also observed in the experiment, which strongly supported the avalanche magnetization mechanism. The novel decrease of the Hc is thought coming from the competing between the TA effect and the instantaneous domain wall motion.

Keywords: rare-earth transition-metal intermetallic compound, ultra-sharp magnetization, coercivity, thermal activation, avalanche magnetization