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Title: Moment-Volume Coupling in La(Fe 1-xSi x) 13

We investigate the origin of the volume change and magnetoelastic interaction observed at the magnetic first-order transition in the magnetocaloric system La(Fe 1-xSix) 13 by means of first-principles calculations combined with the fixed-spin moment approach. Here, we find that the volume of the system varies with the square of the average local Fe moment, which is significantly smaller in the spin disordered configurations compared to the ferromagnetic ground state. The vibrational density of states obtained for a hypothetical ferromagnetic state with artificially reduced spin-moments compared to a nuclear inelastic X-ray scattering measurement directly above the phase transition reveals that the anomalous softening at the transition essentially depends on the same moment-volume coupling mechanism. Finally, in the same spirit, the dependence of the average local Fe moment on the Si content can account for the occurence of first- and second-order transitions in the system.
Authors:
ORCiD logo [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [3] ;  [4] ;  [1]
  1. Univ. of Duisburg-Essen,Duisburg (Germany). Faculty of Physics and Center for Nanointegration (CENIDE)
  2. Leibniz Inst. for Solid State and Materials Research (IFW), Dresden (Germany)
  3. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
  4. Technische Univ. Darmstadt (Germany). Materials Science Division
Publication Date:
Grant/Contract Number:
AC02-06CH11357; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Physica Status Solidi B. Basic Solid State Physics
Additional Journal Information:
Journal Volume: 255; Journal Issue: 2; Journal ID: ISSN 0370-1972
Publisher:
Wiley-Blackwell
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
German Research Foundation (DFG); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Invar effect; La-Fe-Si compounds; density functional theory; magnetocaloric effect; magnetoelastic coupling; nuclear resonanant inelastic x-ray scattering
OSTI Identifier:
1465142
Alternate Identifier(s):
OSTI ID: 1413836