Delocalization and hybridization enhance the magnetocaloric effect in Ni2Mn0.75Cu0.25Ga

摘要: In view of the looming energy crisis facing our planet, attention increasingly focuses on materials potentially useful as a basis for saving technologies. The discovery giant magnetocaloric (GMC) compounds - that exhibit especially large changes in temperature externally applied magnetic field is varied one such compound 1. These have potential use solid state cooling technology viable alternative to existing gas based refrigeration technologies choro-fluoro and hydro-fluoro-carbon chemicals known severe detrimental effect human health environment 2,3. Examples GMC include Gd5(SiGe)4 4, MnFeP1-xAsx 5 Ni-Mn-Ga shape memory alloy 6-8. Here we explain how properties these (Ni2MnGa) can be tuned function by adding dopants. By altering free structural transitions coincide, operates at just right requirements obtained 9. We show Cu, substituted Mn, pulls transition downwards also, counterintuitively, increases delocalization Mn magnetism. At same time, this reinforces Ni-Ga chemical bond, raising martensite-austenite transition. 25percent doping, two coincide 317 K.