Quaternary Heusler alloy Ni2(Mn,Fe)Ga has been studied systematically for the structure, martensitic transformation, and magnetic properties in two systems of Ni50.5Mn25−xFexGa24.5 and Ni50.4Mn28−xFexGa21.6. Substituting Fe for Mn up to about 70%, the pure L21 phase and the thermoelastic martensitic transformation still can be observed in these quaternary systems. Iron doping dropped the martensitic transformation temperature from 220 to 140 K, increased the Curie temperature from 351 to 429 K, and broadened the thermal hysteresis from about 7 to 18 K. Magnetic analysis revealed that Fe atoms contribute to the net magnetization of the material with a moment lower than that of Mn. The temperature dependence of magnetic-field-induced strains has been improved by this doping method.
Co-based Gd3Co29−xCrx compounds with a Nd3(Fe,Ti)29-type of structure have been synthesized successfully for x=6.5 and 7.0. The crystal structure and magnetic properties of the Gd3Co29−xCrx compounds have been investigated by x-ray diffraction analysis and magnetic measurements. It has been found that Gd3(Co,Cr)29 with x=6.5 and 7.0 are of ferrimagnetic compounds with Curie temperature of 412 K for x=6.5 and 359 K for x=7.0, respectively. Temperature dependence of the magnetization shows a compensation point of the magnetization at the certain temperature below the Curie temperature. The intersublattice molecular field coefficient, nRT, was derived to be 3.3 T f.u./μB for Gd3Co22.5Cr6.5 on the basis of the magnetization curve at the compensation temperature. It is noteworthy that the Gd3(Co,Cr)29 compounds exhibit favorable easy-axis anisotropy in the whole temperature range below Curie temperature.
Spin injection efficiency based on conventional and/or half-metallic ferromagnet/semiconductor is greatly limited by the Schmidt obstacle due to conductivity mismatch, here we proposed that by replacing the metallic injectors with spin gapless semiconductors can significantly reduce the conductive mismatch to enhance spin injection efficiency. By performing first principles calculations based on
1.69 Compounds. -All title compounds with x ≤ 0.6 crystallize in the Nd 3 (Fe,Ti) 29 -type structure. Substitution of Ho for Nd leads to a contraction of the unit cell volume. Magnetic measurements indicate that the Curie temperature of the title compounds is almost independent of the Ho content, whereas the saturation moments decrease monotonically with increasing x. For all compounds investigated a spin reorientation from easy plane to easy cone occurs when the temperature decreases from room temperature to 5 K. A tentative spin phase diagram is given. -(WANG*, W. Q.; WANG, J. L.; YAN, Y.; DU, X. B.; WANG, X. F.; JIN, H. M.; J.
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