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The effect of Sb doping on the structure, magnetic properties and magnetocaloric effect of Mn1−xSbxCoGe (x = 0, 0.01, 0.02, 0.04, 0.06) alloys have been investigated. The doping of Sb for Mn results in the decrease of the structural transition temperature (Tt). For compound with x ≤ 0.01, the coupling of the magnetic and structural transitions occurs, leading to so called first-order magnetostructural transition (MST). Continually increasing x to 0.02 leads to decoupling of the magnetic and structural transitions. For x⩾0.04, an interesting phenomenon is appearance of single transition with ferromagnetic transition temperature (TC). For Mn0.99Sb0.01CoGe sample, the maximal value of the magnetic entropy change (ΔSM) attains about 17.7J/kgK, and the refrigerant capacity (RC) can reach about 204 J/kg under a field change of 5 T. The small magnetic hysteresis, and large RC with MST near room temperature would make this alloy system prospectively put into use for room-temperature magnetic refrigeration materials. [ABSTRACT FROM AUTHOR]

Ni48Mn39Sn13-xGex (x = 1, 2) Heusler alloys have been prepared, and the martensitic phase transition (MPT), magnetocaloric effect and exchange bias (EB) have been explored. At room temperature, the structure of both samples presents L21 type, and the MPT shifts to a higher temperature, while the Curie temperature (TC) of the austenitic phase decreases with the increase of the Ge content. The maximum magnetic entropy change of Ni48Mn39Sn13-xGex with x = 2 reaches about 14.67 J/kg K under the magnetic field of 5 T during reverse MPT. In addition, an interesting phenomenon is the enhancement of EB with the increase of the Ge content, especially the abnormal presence of the double-shifted hysteresis loop has been realized in Ni48Mn39Sn13-xGex with x = 2, which can be interpreted by the fact that the antiferromagnetic (AFM) regions couple with proximal ferromagnetic (FM) regions in the opposite way at low temperature. [ABSTRACT FROM AUTHOR]

The structure, phase transitions, magnetocaloric effect, and exchange bias effect in Mn 49 Ni 42- x Co x Sn 9 ( x  = 0, 1, 3 and 5) ferromagnetic shape memory alloys have been systematically investigated. X-ray diffraction results measured at room temperature reveal that Mn 49 Ni 42- x Co x Sn 9 alloys with x  = 0, 1 present martensite structure, and Mn 49 Ni 42- x Co x Sn 9 alloys with x  = 3, 5 exhibit mixture phases of both martensite and austenite. The martensitic transformation and exchange bias field ( H EB ) are very sensitive to the Co content. In addition, large positive magnetic entropy changes were observed in these alloys due to the magnetic-field-induced transition from the paramagnetic martensitic phase to the ferromagnetic austenitic phase, and a large effective refrigeration capacity of 230.8 J/kg was obtained under the magnetic field change of 70 kOe in Mn 49 Ni 37 Co 5 Sn 9 alloy. We realized a continuous tuning of the H EB from 534.7 Oe to 1113.0 Oe after field cooling in presence of 10 kOe. [ABSTRACT FROM AUTHOR]

In this work, we have developed a ferromagnetic shape memory alloy Co50V34Ga16 with a metamagnetic martensitic transformation (MT) from the high-magnetization austenitic phase to the low-magnetization martensitic phase. As a consequence of a strong coupling between structure and magnetic degrees of freedom, the metamagnetic MT of this alloy is relatively sensitive to the external magnetic field, thus giving rise to a field-induced reverse MT. Associated with such a unique behavior, both considerable inverse magnetocaloric effect (9.6 J/kg K) and magnetostrain (0.07%) have also been obtained under the magnetic field change of 3 T. Our experimental results indicate that this kind of Co-V based alloy probably becomes an alternatively promising candidate for applications in magnetic sensors and magnetic refrigeration. [ABSTRACT FROM AUTHOR]