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Title: Magnetic materials at finite temperatures: thermodynamics and combined spin and molecular dynamics derived from first principles calculations

We present a unified approach to describe the combined behavior of the atomic and magnetic degrees of freedom in magnetic materials. Using Monte Carlo simulations directly combined with first principles the Curie temperature can be obtained ab initio in good agreement with experimental values. The large scale constrained first principles calculations have been used to construct effective potentials for both the atomic and magnetic degrees of freedom that allow the unified study of influence of phonon-magnon coupling on the thermodynamics and dynamics of magnetic systems. The MC calculations predict the specific heat of iron in near perfect agreement with experimental results from 300K to above Tc and allow the identification of the importance of the magnon-phonon interaction at the phase-transition. Further Molecular Dynamics and Spin Dynamics calculations elucidate the dynamics of this coupling and open the potential for quantitative and predictive descriptions of dynamic structure factors in magnetic materials using first principles-derived simulations.
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Univ. of Georgia, Athens, GA (United States). Center for Simulational Physics
  3. Univ. of North Carolina, Asheville, NC (United States). Dept. of Physics
  4. Univ. of Tennessee, Knoxville, TN (United States). National Inst. for Computational Sciences
  5. Florida State Univ., Tallahassee, FL (United States). Dept. of Physics
Publication Date:
OSTI Identifier:
1222549
DOE Contract Number:
AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: XXVI IUPAP Conference on Computational Physics, CCP2014, Boston, MA (United States), 11-14 Aug 2014
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF) and Center for Defect Physics (CDP)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; MAGNETIC MATERIALS; COMPUTERIZED SIMULATION; MOLECULAR DYNAMICS METHOD; SPIN; CURIE POINT; IRON; PHONONS; SPECIFIC HEAT; DEGREES OF FREEDOM; MONTE CARLO METHOD; THERMODYNAMICS; STRUCTURE FACTORS; MAGNONS; COUPLING; POTENTIALS; PHASE TRANSFORMATIONS; INTERACTIONS