Giant low field magnetocaloric effect near room temperature in isostructurally alloyed MnNiGe-FeCoGe systems

Abstract

According to the strategy of isostructural alloying, the magnetostructural coupling was realized by doping appropriate stable hexagonal Ni2In-type FeCoGe alloy into MnNiGe systems, which results in the achievement of large magnetization difference and giant low field magnetic entropy change (ΔSm) in the isostructurally alloyed (MnNiGe)-(FeCoGe) systems. Giant ΔSm as much as −51.3 J∙kg-1K−1 at 296 K and −56.2 J∙kg-1K−1 at 275 K under 5 T magnetic field have been observed in (MnNiGe)0.91-(FeCoGe)0.09 and (MnNiGe)0.89-(FeCoGe)0.11 alloys, respectively. Moreover, the ΔSm of (MnNiGe)0.89-(FeCoGe)0.11 alloy are reached −25.6 J∙kg-1K−1 (2 T) and −43.6 J∙kg-1K−1(3 T), respectively. The observed values of -ΔSM under the magnetic field of 2 T and 3 T are larger than most of the reported MnMX(M = Co, Ni and X = Ge, Si) based systems.