Investigation of the complex magnetic behavior of Ni_46.86Co_2.91Mn_38.17Sn_12.06 (at%) magnetic shape memory alloy at low temperatures

Abstract

The magnetic properties, martensitic transformation characteristics, the magnetic field-induced transformation characteristics, and super spin-glass behaviour at low temperature of Ni46.86Co2.91Mn38.17Sn12.06 (at. %) magnetic shape memory alloys (MSMAs) were investigated under various magnetic field levels over temperature intervals from 400 K to 10 K. We observe a small magnetization difference during the martensitic transition evidenced with a visible thermal hysteresis. To investigate the magnetic field induced phase fraction, the minimum magnetic field required to start and complete the magnetostructural phase transition is computed. Super-spin glass features in magnetic data are observed that interacting magnetic clusters are frozen below a critical temperature. Magnetization is computed as a function of temperature at various constant fields using molecular field theory. The critical exponent, β is deduced for the temperature-induced magnetization, which indicates that the MSMA exhibited ferromagnetic ordering during field-cooling and on heating an antiferromagnetic ordering at low temperatures and in low applied magnetic fields. These observations are consistent within the framework of an Ising or Heisenberg model.

Investigation of the inverse magnetocaloric effect with the fraction method

“…The martensite in Heusler alloys has been shown to possess a variety of magnetic configurations such as PM/anti-FM (AFM) or spin glass clusters when cooled to certain temperatures (i.e. the blocking temperature) [29][30][31]. Interestingly, we observed fluctuations in the thermogram on heating (figure 1) above A f .…”

Tuning of the magneto-caloric effects in Ni43Mn46In11 magnetic shape memory alloys by substitution of boron

“…The insets of figures 4(a) and (b) shows the low-temperature range M(T) data. Interestingly, at low temperatures, there exists the presence of a peak in the ZFC plot is attributed as a spin glass peak [50,51], T G of Ni 43 Mn 45.3 B 0.7 In 11 and Ni 43 Mn 45.0 B 1.0 In 11 was observed at 96 K and 91 K, respectively. The existence of spin glass peak was explained to be due to the result of mixed magnetic interactions between ferromagnetic and antiferromagnetic clusters [50,51].…”

“…Interestingly, at low temperatures, there exists the presence of a peak in the ZFC plot is attributed as a spin glass peak [50,51], T G of Ni 43 Mn 45.3 B 0.7 In 11 and Ni 43 Mn 45.0 B 1.0 In 11 was observed at 96 K and 91 K, respectively. The existence of spin glass peak was explained to be due to the result of mixed magnetic interactions between ferromagnetic and antiferromagnetic clusters [50,51]. Among the other things, there exist a hysteresis between FC and FH curves for all applied magnetic fields which is quite evident for 100 Oe measurement reported in our previous studies [25,52].…”