Magnetic Phase Transition and Exchange Bias in Ni45Co5Mn35.5In14.5 Heusler Alloy

Magnetic properties and exchange bias of Ni45Co5Mn35.5In14.5 ribbons were investigated by vibrating sample magnetometry (VSM) and electron magnetic resonance (EMR). Curie temperatures determined by using VSM and EMR methods are equal to 374K and 377K, respectively. Additionally, the EMR measurements revealed the existence of a weak ferromagnetic resonance (FMR) line in the paramagnetic region. The upward deviation of the integral intensity from Curie-Weis low below temperature T and above TC confirms the existence of ferromagnetic phase in this temperature region. Below TC, the integral intensity does not saturate, which can suggest the coexistence of different magnetic phases at low temperature range. Additional confirmation on the coexistence of magnetic phases in the sample are asymmetric hysteresis loops associated with the spontaneous exchange bias effect. The dependence of EMR signal on cyclic repetition of measurement is also discussed.