Martensitic phase transition with magnetocaloric effect and double-shifted exchange bias in the martensitic phase for Ni₄₈Mn₃₉Sn_13-xGe_x alloys

ABSTRACT

Ni₄₈Mn₃₉Sn_13-xGe_x (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 (T_C) of the austenitic phase decreases with the increase of the Ge content. The maximum magnetic entropy change of Ni₄₈Mn₃₉Sn_13-xGe_x 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 Ni₄₈Mn₃₉Sn_13-xGe_x 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.

KEYWORDS:

• Heusler alloy
• martensitic phase transition
• magnetocaloric effect
• exchange bias

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [Grant Number 51371111].