Invited Paper AC+AS+MI+SA+SS-MoA8
Electronic Structure, Magnetic Properties, and Magneto-Structural Transformations of Rare Earth Magneto-Caloric Materials
Monday, November 10, 2014, 4:20 pm, Room 301
| Session: |
Theoretical Modeling of f Electron Systems |
| Presenter: |
Durga Paudyal, Ames Laboratory |
| Authors: |
D. Paudyal, Ames Laboratory
V.K. Pecharsky, Ames Laboratory and Iowa State University
K.A. Gschneidner, Jr., Ames Laboratory and Iowa State University
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| Correspondent: |
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We present first principles modeling of structural and magnetic properties of Gd5Ge4 based magneto-caloric materials. The total energy as a function of the shear displacement of slabs confirms stability of experimentally observed crystal and magnetic structures. Small substitutions of the Gd by Y and Lu lead to a catastrophic loss of ferromagnetism, but the substitutions by La have no effect on the magnetism. Furthermore, substitutions of the Ge by Si exert chemical pressure and transform the antiferromagnetic O(II) to the ferromagnetic O(I) ground state. In addition, we present a pathway for estimating the magnetic entropy change in the room temperature giant magnetocaloric compounds, i.e. Gd5Si2Ge2, by coupling first principles outputs with the established magneto-thermodynamic models. The theoretical values of the magnetic entropy change compare well with experimental results. This work was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Science and Engineering Division. The research was performed at the Ames Laboratory, which is operated for the U.S. DOE by Iowa State University under contract # DE-AC02-07CH11358.