The inverse magnetocaloric effect associated with the martensitic transition in the ${\mathrm{Ni}}_{45.4}{\mathrm{Mn}}_{41.5}{\mathrm{In}}_{13.1}$ Heusler alloy is reported. A large positive magnetic entropy change of $8\mathrm{J}∕\mathrm{kg}\mathrm{K}$ under a low magnetic field of $10\mathrm{kOe}$ is found near the martensitic transition temperature. This change originates from the first-order transition from a low-temperature weak-magnetic martensitic phase to a high-temperature ferromagnetic austenitic phase. The large low-field magnetic entropy change indicates a great potential of Ni–Mn–In alloys as working materials for magnetic refrigeration in a wide temperature range.

The low-field magnetic entropy changes in ${\mathrm{Ni}}_{50-x}{\mathrm{Mn}}_{39+x}{\mathrm{Sn}}_{11}$ alloys ($x=5$ , 6, and 7) were investigated. The martensitic transition shifts to lower temperature with the increase of Mn concentration. Under an applied magnetic field of $10\mathrm{kOe}$ , the magnetic entropy changes are 6.8, 10.1, and $10.4\mathrm{J}∕\mathrm{kg}\mathrm{K}$ , for $x=5$ , 6, and 7, respectively. The large entropy change in ${\mathrm{Ni}}_{50-x}{\mathrm{Mn}}_{39+x}{\mathrm{Sn}}_{11}$ can be attributed to the sharp magnetization change associated with the martensitic transition from a ferromagnetic parent phase to a weak-magnetic martensitic phase. The large low-field magnetic entropy change and low cost suggest ${\mathrm{Ni}}_{50-x}{\mathrm{Mn}}_{39+x}{\mathrm{Sn}}_{11}$ alloy as the promising magnetic refrigerant.

Rational design of bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) with excellent activity and stab

Phase transitions and magnetic entropy changes are studied in ${\text{Mn}}_{1.9-x}{\text{Ni}}_x\text{Ge}$ ($x=0.85$ , 0.855) alloys. In these off-stoichiometric alloys, the crystallographic transition temperature decreases remarkably due to the deficiency of transition-metal atoms, and, consequently, a magnetostructural transition from the antiferromagnetic TiNiSi-type structure to the ferromagnetic ${\text{Ni}}_2\text{In}$ -type structure is observed. Owing to the abrupt change in magnetization, large magnetic entropy changes are obtained. The effect of transition-metal vacancies on the phase transition temperature is discussed.

The exchange bias properties have been investigated in bulk ${\text{Mn}}_{50}{\text{Ni}}_{40-\text{x}}{\text{Sn}}_{10+\text{x}}$ ($\text{x}=0$ , 0.5, and 1) Heusler alloys with high content of Mn, in which the largest exchange bias field is up to 910 Oe for ${\text{Mn}}_{50}{\text{Ni}}_{40}{\text{Sn}}_{10}$ alloy. In these alloys, the excess Mn atoms would occupy not only the Sn sites but also the Ni sites, and the moments of Mn on Sn or Ni sites are coupled antiferromagnetically to those on the regular Mn sites, respectively. The origin of this considerably large exchange bias field has been discussed.