Multiscale modeling of ultrafast element-specific magnetization dynamics of ferromagnetic alloys

Hinzke, Denise; Atxitia, Unai; Carva, Karel; Nieves, P.; Chubykalo‐Fesenko, O.; Oppeneer, Peter M.; Nowak, Ulrich

doi:10.1103/physrevb.92.054412

Cited by 45 publications

(37 citation statements)

References 48 publications

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“…The new equation constitutes an important step forward in the description of the dynamics of two-coomponent alloys, such as ferrimagnets which are traditionally modelled using two coupled macroscopic LL equations. The two-component LLB equation has been already successfully applied to model FeCoGd [31] and more recently to FeNi [37] showing that sublattices have distinct dynamics, in agreement with experimental findings. Also the FMR and exchange modes in ferrimagnets and their temperature dependence are better understood within this approach [38].…”

Section: Discussionsupporting

confidence: 73%

The classical two-sublattice Landau–Lifshitz–Bloch equation for all temperatures

Nieves

Atxitia

Chantrell

et al. 2015

Low Temperature Physics

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Micromagnetic modeling has proved itself as a widely used tool, complimentary in many respects to experimental measurements. The Landau-Lifshitz equation provides a basis for this modeling, especially where the dynamical behaviour is concerned. However, this approach is strictly valid only for zero temperature and for high temperatures must be replaced by a more thermodynamically consistent approach such as the the LandauLifshitz-Bloch (LLB) equation. Here we review the recently derived LLB equation for two-sublattice systems and extend its derivation for temperatures above the Curie temperature. We present comparison with many-body atomistic simulations and show that this equation can describe the ultra-fast switching in ferrimagnets, observed experimentally.PACS: 75.10.Hk Classical spin models; 75.Magnetic properties and materials; 75.78.-n Magnetization dynamics.

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Section: Discussionsupporting

confidence: 73%

The classical two-sublattice Landau–Lifshitz–Bloch equation for all temperatures

Nieves

Atxitia

Chantrell

et al. 2015

Low Temperature Physics

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“…In both cases, introducing the phonon temperature induces an improvement, but only by a few percent or less. In the case of disordered Py, our theoretical result outclasses previous methods: ASD returns T c = 656 K using J ij (0 K), consistent with other works using CPA [45], while within R-ASD, T c increases to 844 K, which considerably improves the agreement with experiments. This level of agreement may be fortuitous, but the amplitude of the correction shows that the renormalization of the exchange J ρη ij with lattice temperature is crucial.…”

Section: Magnetization and Curie Temperaturesupporting

confidence: 79%

Competition of lattice and spin excitations in the temperature dependence of spin-wave properties

et al. 2018

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(2018). Competition of lattice and spin excitations in the temperature dependence of spin-wave properties. Physical Review B (PRB), 97 (21). The interplay of magnons and phonons can induce strong temperature variations in the magnetic exchange interactions, leading to changes in the magnetothermal response. This is a central mechanism in many magnetic phenomena, and in the new field of Spin Caloritronics, which focuses on the combination of heat and spin currents. Boson model systems have previously been developed to describe the magnon-phonon coupling but, until recently, studies rely on empirical parameters. In this paper, we propose a first-principles approach to describe the dependence of the magnetic exchange integrals on phonon renormalization, leading to changes in the magnon dispersion as a function of temperature. The temperature enters into the spin dynamics (by introducing fluctuations) as well as in the magnetic exchange itself. Depending on the strength of the coupling, these two temperatures may or may not be equilibrated, yielding different regimes. We test our approach in typical and well-known ferromagnetic materials: Ni, Fe, and Permalloy. We compare our results to recent experiments on the spin-wave stiffness, and discuss departures from Bloch's law and parabolic dispersion. Copyright and re-use policy

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“…As mentioned, it implies a magnetization nutation i.e., a changing of the precession angle as time progresses. Without the inertia term we obtain the well-known LLG equation of motion that has already been used extensively in magnetization dynamics simulations (see, e.g., [61][62][63][64][65]). …”

Section: Magnetization Dynamicsmentioning

confidence: 99%

Relativistic theory of magnetic inertia in ultrafast spin dynamics

et al. 2017

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The influence of possible magnetic inertia effects has recently drawn attention in ultrafast magnetization dynamics and switching. Here we derive rigorously a description of inertia in the Landau-Lifshitz-Gilbert equation on the basis of the Dirac-Kohn-Sham framework. Using the FoldyWouthuysen transformation up to the order of 1/c 4 gives the intrinsic inertia of a pure system through the 2 nd order time-derivative of magnetization in the dynamical equation of motion. Thus, the inertial damping I is a higher order spin-orbit coupling effect, ∼ 1/c 4 , as compared to the Gilbert damping Γ that is of order 1/c 2 . Inertia is therefore expected to play a role only on ultrashort timescales (sub-picoseconds). We also show that the Gilbert damping and inertial damping are related to one another through the imaginary and real parts of the magnetic susceptibility tensor respectively.

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Multiscale modeling of ultrafast element-specific magnetization dynamics of ferromagnetic alloys

Cited by 45 publications

References 48 publications

The classical two-sublattice Landau–Lifshitz–Bloch equation for all temperatures

The classical two-sublattice Landau–Lifshitz–Bloch equation for all temperatures

Competition of lattice and spin excitations in the temperature dependence of spin-wave properties

Relativistic theory of magnetic inertia in ultrafast spin dynamics

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