Magnetocaloric and magnetoresistance properties in Co-based (Co_0.402Fe_0.201Ni_0.067B_0.227Si_0.053Nb_0.05)_100−xCu_x (x=0–1) glassy alloys

Abstract

The magnetocaloric and magnetoresistance properties of amorphous Co-based (Co_0.402Fe_0.201Ni_0.067B_0.227Si_0.053Nb_0.05)_100−xCu_x (x = 0, 0.5, 0.75 and 1) ribbons were investigated. Cu additions changed the crystallisation temperature (T_x) and the Curie temperature (T_C). The saturation magnetisation (M_s) and coercivity (H_c) for alloys were in the range of 65.51–38.49 emu/g and 1.99–6.84 A/m, respectively. Under an applied magnetic field change of 2.2 T, the (−ΔS_M)^max for (Co_0.402Fe_0.201Ni_0.067B_0.227Si_0.053Nb_0.05)_100−xCu_x with x = 0, 0.5, 0.75 and 1 are 0.77, 0.71, 0.89 and 0.67 Jkg⁻¹ K⁻¹, respectively. The values of refrigeration capacity (RC) for the as-spun glassy alloys are comparable with those of previously studied Fe-based metallic glasses such as Fe₈₀B₁₀Zr₉Cu₁, (Fe_0.76B_0.24)₉₆Nb₄ and Fe₈₂Ni₂Zr₆B₁₀. In addition, the maximum magnetoresistance (MR) values for (Co_0.402Fe_0.201Ni_0.067B_0.227Si_0.053Nb_0.05)_100−xCu_x with x = 0, 0.5, 0.75 and 1 are found to be 110, 38, 23 and 1% around the Curie temperatures under an applied magnetic field change of 1 T, respectively. With good RC, negligible hysteresis due to very low coercivity values and large magnetoresistance, these Co-based amorphous alloys can be used as the high temperature magnetic refrigerants and multifunctional applications working in the temperature range of 450–600 K.

Keywords:

• Metallic glasses
• magnetocaloric effect
• magnetic entropy change
• magnetoresistance