Magnetocaloric effect and temperature -dependent magnetoresistance in Cu-doped FeCoNiBSiNb amorphous alloys

Abstract

In this work, magnetocaloric and magnetoresistance properties of Fe-based (Fe(0.402)Co(0.201)Ni(0.067)Bo(0.227)Si(0.053)Nb(0.05))(100-x)Cu-x (x = 0, 0.5, 0.75, 1) amorphous ribbons formed by melt-spinning method and the effect of Cu on these properties were investigated. Curie temperature (T-C) was not changed with the addition of Cu up to 0.5% to the composition. On the other hand, for Fe-based (Fe(0.402)Co(0.201)Ni(0.067)Bo(0.227)Si(0.053)Nb(0.05))(100-x)Cu-x (x = 0.75 and 1), T-C increased from 505 K (for x = 0.5) to 526 K (for x = 0.75) and almost remain constant for x = 1. Maximum magnetic entropy change (-Delta S-M)(max) and refrigeration capacity (RC) values were found to be in the range of 0.62-1.25 Jkg(-1)K(-1) and 62-158.75 Jkg(-1) respectively for (Fe(0.402)Co(0.201)Ni(0.067)Bo(0.227)Si(0.053)Nb(0.05))(100-x)Cu-x (x = 0, 0.5, 0.75, 1) amorphous ribbons under a maximum field of 2 T. These values are comparable with those of previously studied Fe-based metallic glasses. In addition, the maximum temperature dependent magnetoresistance (MR (%)) values for (Fe(0.402)Co(0.201)Ni(0.067)Bo(0.227)Si(0.053)Nb(0.05))(100-x)Cu-x (x = 0, 0.5, 0.75, 1) were found to be 125, 17, 7, and 1% around the Curie temperatures under an applied field of 1 T, respectively. The magnetoresistance values of Cu-free Fe-based glassy alloy are higher than those of Cu-doped alloys. The results show that appropriate amount of Cu substitution (x = 0.75, 1) can enhance the RC and (-Delta S-M)(max). The suitable RC, large magnetoresistance, good thermal stability, and negligible hysteresis offer that these Fe-based glassy alloys exhibit promising applications as high-temperature magnetic refrigerants and multifunctional materials working in the temperature range of 400-600 K.