Effect of annealing on the magnetic ordering and electron magnetic resonance of melt-spun Ni-Mn-In ribbons

In this study, the electron magnetic resonance (EMR) spectra of annealed Ni50Mn355In45 Heusler alloy ribbons within the temperature range 240 K <= T <= 360 K are investigated. In the paramagnetic region, the temperature dependence of the EMR linewidth is governed by the Korringa relaxation process. The g value exhibits a positive shift, which indicates a non-bottleneck regime. The temperature dependence of inverse integrated intensity exhibits a Curie-Weiss like behaviour with T-C equals 298 K. The effects of annealing on the magnetic and structural ordering are discussed. Annealing increases the Curie temperature and changes the first-order phase transition temperature. Additionally, the low-field microwave absorption peak appears below the magnetic ordering temperature.