Magneto-optical spectra of polycrystalline samples of the Fe 48 Mn 24 Ga 28 Heusler alloy undergoing martensitic transformation from the high-temperature paramagnetic austenitic to ferromagnetic martensitic phase have been studied at 50–320 K in the transversal Kerr effect geometry. A comparison of magnetooptical spectra with data obtained in magnetic measurements has demonstrated that the martensitic transition on the surface of a sample and in its bulk takes place in the same temperature interval. Magnetic anisotropy has been found in the martensitic phase driven by large multidomain inclusions of martensite in austenite. The magneto-optical signal of Fe 48 Mn 24 Ga 28 differs strongly in spectral shape from that measured in Ni-Mn-Ga.

The concentration dependence of the coefficient R s characterizing the anomalous Hall effect (AHE) has been studied by measuring the electrical resistivity ρ, magnetoresistance, and the magnetic field dependence of magnetization and Hall resistivity of (Co41Fe39B20) x (Al-O)100 − x nanocomposite thin films. It has been demonstrated that the AHE coefficient increases by more than an order of magnitude with a decrease in the percentage x of the amorphous ferromagnetic metal from 60 to 30 and its behavior is described by the relation R s ∼ ρ m , where m = 0.46 ± 0.1. At the same time, the coefficient characterizing the normal Hall effect grows by a factor of less than 10. The mechanisms underlying the giant Hall effect in nanocomposites have been discussed.

A correlation between the magnetic part of the entropy and magnetoresistance has been studied using measurements of the resistivity, magnetoresistance, and magnetization of the Ni 50 Mn 35 In 12 Si 3 and Ni 50 Mn 35 In 11 Si 4 Heusler alloys. It has been shown that although the variations of the entropy and the magnetoresistance are observed to be maximal within the same temperature intervals in the vicinity of the first-order and second-order phase transitions, there is no universal correlation between these effects.

Magnetotransport properties of an Fe48Mn24Ga28 Heusler-based ferromagnetic shape memory alloy are tracked in a temperature interval that covers both martensitic and austenitic phases. A large temperature hysteresis indicative of a coupled magnetostructural transition from ferromagnetic martensite to paramagnetic austenite is observed on the temperature dependencies of magnetization and electrical resistivity. The temperature dependency of the anomalous Hall-effect coefficient in Fe48Mn24Ga28 cannot be described in terms of skew scattering, side-jump, and intrinsic mechanisms of the anomalous Hall-effect theory. The Hall-effect resistivity in the martensitic state is smaller, but is of the same order of magnitude as in the case of the giant Hall effect in a half-metallic Co2MnAl. Specific features of the temperature dependencies of magnetization, resistivity, magnetoresistance, and ordinary and anomalous Hall-effect coefficients are discussed and the possible routes for increasing Hall-effect resistivity are suggested.

The magnetocaloric properties of the Ni50Mn34.8In14.2B Heusler alloy have been studied by direct measurements of the adiabatic temperature change (ΔTAD(T,H)) and indirectly by magnetization (M(T,H)), differential scanning calorimetry, and specific heat (C(T,H)) measurements. The presence of a first-order ferromagnetic-paramagnetic transition has been detected for Ni50Mn34.8In14.2B at 320 K. The magnetocaloric parameters, i.e., the magnetic entropy change (ΔSM = (2.9-3.2) J/kgK) and the adiabatic temperature change (ΔTAD = (1.3-1.52) K), have been evaluated for ΔH = 1.8 T from CP(T,H) and M(T,H) data and from direct ΔTAD(T,H) measurements. The extracted magnetocaloric parameters are comparable to those of Gd.

The magnetocaloric properties of Ni-Mn-In-B Heusler alloy have been studied using direct measurements of the adiabatic temperature change (Δ T AD ( T , H )) , and indirectly by magnetization ( M ( T , H )), differential scanning calorimetry, and specific heat ( C P ( T , H )) measurements. The presence of a first-order ferromagnetic-paramagnetic transition has been detected for Ni 50 Mn 34.8 In 14.2 B at 320 K. The magnetocaloric parameters, i.e., the magnetic entropy change, Δ S M = (2.9-3.2) J/kgK, and the adiabatic temperature change, Δ T AD = (1.3-1.52) K, have been evaluated for Δμ 0 H = 1.8 T from C P ( T , H ) and M(T,H), and from C P ( T , H ) and direct Δ T AD ( T , H ) measurements, respectively, in the vicinity of the first-order transition temperature. The extracted magnetocaloric parameters are comparable to that of Gd.