Collective dynamics in atomistic models with coupled translational and spin degrees of freedom

Perera, Dilina; Nicholson, Don M.; Eisenbach, Markus; Stocks, G. M.; Landau, D. P.

doi:10.1103/physrevb.95.014431

Cited by 33 publications

(25 citation statements)

References 64 publications

(99 reference statements)

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“…Overall our results compare well with [110][111][112] (experimental) and theoretical 58,113 (theory) phonon dispersions at finite temperature, and with 114 (experiment) and 91 (theory) magnon dispersions.…”

Section: Bcc Fe Magnon and Phonon Dispersionssupporting

confidence: 83%

“…15 are the peak positions of the magnon dispersions at different temperature, obtained by means of fitting to a Lorentzian function. In the very detailed investigations by Perera et al 58 of magnon and phonon spectra of the Dudarev-Derlet potential 54,55 potential for bcc Fe, the measure (ω SLD (Q) − ω SD (Q))/ω SD (Q) was used to analyze the temperature-dependent influence of exchange striction on magnon dispersion. Similarly, the quantity (ω SLD (Q) − ω LD (Q))/ω LD (Q) was defined for the phonon dispersions.…”

Section: Bcc Fe Magnon and Phonon Dispersionsmentioning

confidence: 99%

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General method for atomistic spin-lattice dynamics with first-principles accuracy

et al. 2019

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We present a computationally efficient general first-principles based method for spin-lattice simulations for solids and clusters. The method is based on a coupling of atomistic spin dynamics and molecular dynamics simulations, expressed through a spin-lattice Hamiltonian, where the bilinear magnetic term is expanded up to second order in displacement. The effect of first order spin-lattice coupling on the magnon and phonon dispersion in bcc Fe is reported as an example, and we observe good agreement with previous simulations. In addition, we also illustrate the coupled spin-lattice dynamics method on a more conceptual level, by exploring dissipation-free spin and lattice motion of small magnetic clusters (a dimer, trimer and quadmer). The here discussed method opens the door for a quantitative description and understanding of the microscopic origin of many fundamental phenomena of contemporary interest, such as ultrafast demagnetization, magnetocalorics, and spincaloritronics. arXiv:1804.03119v2 [cond-mat.mtrl-sci] 9 Jul 2018

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Section: Bcc Fe Magnon and Phonon Dispersionssupporting

confidence: 83%

Section: Bcc Fe Magnon and Phonon Dispersionsmentioning

confidence: 99%

General method for atomistic spin-lattice dynamics with first-principles accuracy

et al. 2019

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“…In other words, the spin and lattice systems should be treated at the same finite temperature. However, none of the aforementioned first-principles calculations of phonons in Fe simulates both the lattice and the magnetic system at the same finite temperature [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Effect of thermal lattice and magnetic disorder on phonons in bcc Fe: A first-principles study

2019

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We present a first-principles theoretical approach to calculate temperature dependent phonon dispersions in bcc Fe, which captures finite temperature spin-lattice coupling by treating thermal disorder in both the spin and lattice systems simultaneously. With increasing temperature, thermal atomic displacements are found to induce increasingly large fluctuations in local magnetic moment magnitudes. The calculated phonon dispersions of bcc Fe show excellent agreement with measured data over a wide range of temperatures both above and below the magnetic and structural transition temperatures, suggesting the applicability of the developed approach to other magnetic materials.

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“…The understanding of how spin and lattice degrees of freedom interact is of fundamental importance [1,2]. Recently, strong evidence was found for the existence of a significant coupling between magnons and phonons for instance in bcc Fe [3,4] and the ferromagnetic semiconductor EuO [5]. Spinlattice coupling is central for seemingly disparate phenomena such as the mechanical generation of spin currents by spinrotation coupling [6], the spin-Seebeck effect [7,8], and the driving of magnetic bubbles with phonons [9].…”

Section: Introductionmentioning

confidence: 99%

Microscopic theory for coupled atomistic magnetization and lattice dynamics

Fransson

Thonig

Bessarab

et al. 2017

Phys. Rev. Materials

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A coupled atomistic spin and lattice dynamics approach is developed which merges the dynamics of these two degrees of freedom into a single set of coupled equations of motion. The underlying microscopic model comprises local exchange interactions between the electron spin and magnetic moment and the local couplings between the electronic charge and lattice displacements. An effective action for the spin and lattice variables is constructed in which the interactions among the spin and lattice components are determined by the underlying electronic structure. In this way, expressions are obtained for the electronically mediated couplings between the spin and lattice degrees of freedom, besides the well known inter-atomic force constants and spin-spin interactions. These former susceptibilities provide an atomistic ab initio description for the coupled spin and lattice dynamics. It is important to notice that this theory is strictly bilinear in the spin and lattice variables and provides a minimal model for the coupled dynamics of these subsystems and that the two subsystems are treated on the same footing. Questions concerning time-reversal and inversion symmetry are rigorously addressed and it is shown how these aspects are absorbed in the tensor structure of the interaction fields. By means of these results regarding the spin-lattice coupling, simple explanations of ionic dimerization in double anti-ferromagnetic materials, as well as, charge density waves induced by a non-uniform spin structure are given. In the final parts, a set of coupled equations of motion for the combined spin and lattice dynamics are constructed, which subsequently can be reduced to a form which is analogous to the Landau-Lifshitz-Gilbert equations for spin dynamics and damped driven mechanical oscillator for the ionic motion. It is important to notice, however, that these equations comprise contributions that couple these descriptions into one unified formulation. Finally, Kubo-like expressions for the discussed exchanges in terms of integrals over the electronic structure and, moreover, analogous expressions for the damping within and between the subsystems are provided. The proposed formalism and new types of couplings enables a step forward in the microscopic first principles modeling of coupled spin and lattice quantities in a consistent format.

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Collective dynamics in atomistic models with coupled translational and spin degrees of freedom

Cited by 33 publications

References 64 publications

General method for atomistic spin-lattice dynamics with first-principles accuracy

General method for atomistic spin-lattice dynamics with first-principles accuracy

Effect of thermal lattice and magnetic disorder on phonons in bcc Fe: A first-principles study

Microscopic theory for coupled atomistic magnetization and lattice dynamics

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