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

摘要

According to the strategy of isostructural alloying, the magnetostructural coupling was realized by doping appropriate stable hexagonal Ni_2In-type FeCoGe alloy into MnNiGe systems, which results in the achievement of large magnetization difference and giant low field magnetic entropy change (ΔS_m) in the isostructurally alloyed (MnNiGe)-(FeCoGe) systems. Giant ΔS_m as much as -51.3 J·kg~(-1)K~(-1) at 296 K and -56.2 J·kg~(-1)K~(-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 ΔS_m of (MnNiGe)_(0.89)-(FeCoGe)_(0.11) alloy are reached - 25.6 J·kg~(-1)K~(-1) (2 T) and -43.6 J·kg~(-1)K~(-1)(3 T), respectively. The observed values of -ΔS_m 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.