Delocalization and hybridization enhance the magnetocaloric effect in Cu-doped Ni2 MnGa
The structural and magnetic transitions in the shape-memory alloy Ni2 MnGa can be tuned as a function of temperature by adding dopants. By altering the free energy such that the structural and magnetic transitions coincide, a giant magnetocaloric effect is created near room temperature. We show, using x-ray absorption spectroscopy and x-ray magnetic circular dichroism, how Cu, substituted for Mn, pulls the magnetic transition downward in temperature and also, counterintuitively, increases the delocalization of the Mn magnetism. At the same time, this reinforces the Ni-Ga chemical bond, raising the temperature of the martensite-austenite transition. At 25% doping, the two transitions coincide at 317 K. © 2009 The American Physical Society.
Publication Source (Journal or Book title)
Physical Review B - Condensed Matter and Materials Physics
Roy, S., Blackburn, E., Valvidares, S., Fitzsimmons, M., Vogel, S., Khan, M., Dubenko, I., Stadler, S., Ali, N., Sinha, S., & Kortright, J. (2009). Delocalization and hybridization enhance the magnetocaloric effect in Cu-doped Ni2 MnGa. Physical Review B - Condensed Matter and Materials Physics, 79 (23) https://doi.org/10.1103/PhysRevB.79.235127