Pui-Wai Ma S.L. Dudarev C.H. Woo
Spin–lattice dynamics generalizes molecular dynamics to magnetic materials, where dynamic variables describing an evolving atomic system include not only coordinates and velocities of atoms but also directions and magnitudes of atomic magnetic moments (spins). Spin–lattice dynamics simulates the collective time evolution of spins and atoms, tak…
PublishedC. H. Woo Haohua Wen A. A. Semenov S. L. Dudarev Pui-Wai Ma
Quantization of spin-wave excitations necessitates the reconsideration of the classical fluctuation-dissipation relation (FDR) used for temperature control in spin-lattice dynamics simulations of ferromagnetic metals. In this paper, Bose-Einstein statistics is used to reinterpret the Langevin dynamics of both lattice and spins, allowing quantum sta…
PublishedPui-Wai Ma S. L. Dudarev C. H. Woo
We develop an atomistic spin-lattice-dynamics model for simulating energy relaxation in magnetic materials. The model explicitly solves equations of motion for the atoms and spins, and includes interaction with electron excitations. We apply the model to simulate the dynamics of propagation of a compressive elastic wave in iron. We find that coupli…
PublishedPui-Wai Ma W. C. Liu C. H. Woo S. L. Dudarev
We perform large-scale molecular dynamics simulations to study the magnetic properties of amorphous iron under pressure. Simulations, exceeding by at least two orders of magnitude those accessible to density functional calculations, use the recently developed magnetic interatomic potential for iron. The distributions of the size of atomic magnetic …
PublishedPui-Wai Ma C. H. Woo S. L. Dudarev
Finite temperature magnetic properties of iron thin films are investigated, up to ferro/paramagnetic transition. The coupled dynamics of atoms and magnetic moments is treated using large-scale spin-lattice dynamics (SLD) simulations. A comprehensive study of surface and bulk magnetic properties is conducted, to investigate their dependences on temp…
PublishedPui-Wai Ma C. H. Woo
We develop a dynamical simulation model for magnetic iron where atoms are treated as classical particles with intrinsic spins. The atoms interact via scalar many-body forces as well as via spin orientation dependent forces of the Heisenberg form. The coupling between the lattice and spin degrees of freedom is described by a coordinate-dependent exc…
PublishedPui-Wai Ma C. H. Woo S. L. Dudarev
We develop a Spin-Lattice Dynamics (SLD) simulation model for ferromagnetic iron where atoms are treated as classical particles with spins. The atoms interact via many-body forces as well as via spin-orientation-dependent forces of the Heisenberg form. The coupling between the lattice and the spin degrees of freedom is described by a coordinate-dep…
PublishedS. L. Dudarev A. A. Semenov C. H. Woo
We investigate the dynamics of nucleation and the growth of voids in an irradiated material in the presence of a spatially heterogeneous dislocation microstructure. We find that, due to the sensitivity of the void nucleation rate to the local vacancy supersaturation, voids nucleate and grow almost exclusively in the regions where the density of dis…
PublishedS. L. Dudarev A. A. Semenov C. H. Woo
We found that by assuming that the density of dislocations in an irradiated material varies as a function of the distance to grain boundaries and that mobile interstitial defect clusters perform three-dimensional diffusional motion it is possible to achieve significantly better agreement with experimental observations of profiles of heterogeneous v…
Published