Static critical exponents, anisotropy, Hall and magneto-caloric effects, and magnetic interactions in FeCr, FeCo, and MnFe-based alloy ribbons

This paper presents a comparative study of the critical exponents (beta, gamma, delta), the critical temperature Tc, the magnetic anisotropy, the Hall and magneto-caloric effects, and the magnetic interactions for the alloys [(Fe50Co50)(75)B20Si5](96)Nb-4, Fe65.5Cr8Cu1Nb3Si13.5B9, and Mn50Ni36Fe5Sn9 prepared by using melt-spinning. The above critical parameters and the magneto-caloric effect were determined from magnetization measurements. The values (beta, delta, T-C) for [(Fe50Co50)(75)B20Si5](96)Nb-4 and Fe65.5Cr8Cu1Nb3Si13.5B9 were (0.34 +/- 0.09; 4.50 +/- 0.45; 660 +/- 30 K) and (0.52 +/- 0.04; 3.62 +/- 0.06; 481 +/- 2 K), respectively, and for Mn50Ni36Fe5Sn9 it was (0.51 +/- 0.03; 2.97 +/- 0.03; 318 +/- 8 K). The Hall resistivity vs. H curves exhibit an H-S inflection field below which ordinary and extraordinary Hall effects are observed. Above H-S, the ordinary Hall effect predominates and the extraordinary one is no longer seen. The H-S values for [(Fe50Co50)(75)B20Si5](96)Nb-4 and Fe65.5Cr8Cu1Nb3Si13.5B9 were 8 kOe and 4.42 kOe, respectively, and for Mn50Ni36Fe5Sn9, 1.84 kOe. The number of charge carriers, n(c), was determined for H > H-S, and its value for Fe50Co50)(75)B20Si5](96)Nb-4 and Mn50Ni36Fe5Sn9 was 2.71 x 10(19) cm(-3) and 129 x 10(19) cm(-3), respectively. The change in magnetic entropy and relative cooling capacity due to a field change of 10 kOe were evaluated and their maximum values close to T-C for [(Fe50Co50)(75)B20Si5](96)Nb-4 and Fe65.5Cr8Cu1Nb3Si13.5B9 were (0.6; 0.75) Jkg(-1)K(-1) and (57.4; 56.6) Jkg(-1), respectively, and for M50Ni36Fe5Sn9, 0.5 Jkg(-1)K(-1) and 25.1 Jkg(-1), respectively. The possible effects of the exchange and spin-orbit interactions on the above results were also analyzed.