Spin dynamics with inertia in metallic ferromagnets

Kikuchi, Toru; Tatara, Gen

doi:10.1103/physrevb.92.184410

Cited by 55 publications

(42 citation statements)

References 33 publications

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“…The very last term in Eq. (24) has been associated previously with the inertia magnetization dynamics [32,59,60]. As mentioned, it implies a magnetization nutation i.e., a changing of the precession angle as time progresses.…”

Section: Magnetization Dynamicsmentioning

confidence: 83%

“…Similarly, it can be expected that the inertial damping will become modified through environmental influences. An example of environmental effects that can lead to magnetic inertia have been considered previously, for the case of a local spin moment surrounded by conduction electrons, whose spins couple to the local spin moment and affect its dynamics [31,32].…”

Section: Discussionmentioning

confidence: 99%

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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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Section: Magnetization Dynamicsmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Relativistic theory of magnetic inertia in ultrafast spin dynamics

et al. 2017

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“…Conclusions.-Inertia effects in spin dynamics have been discussed intensively in the recent years, mainly in the context of applications for magnetic devices [15][16][17][18][19][20][21][22][23][24][25][26][27]. The most fundamental system which covers the essentials of spin dynamics, however, namely a single spin coupled to a Fermi sea has not yet been addressed in this respect.…”

mentioning

confidence: 99%

“…The resulting nutation of the spin motion has been introduced and studied phenomenologically [17,18] or with realistic parameters taken from firstprinciples calculations [19] but can also be derived on a microscopic level [20][21][22] within the general framework of semiclassical spin dynamics [23][24][25].…”

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confidence: 99%

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Inertia effects in the real-time dynamics of a quantum spin coupled to a Fermi sea

Sayad

Rausch

Potthoff

2016

EPL

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-Spin dynamics in the Kondo impurity model, initiated by suddenly switching the direction of a local magnetic field, is studied by means of the time-dependent density-matrix renormalization group. Quantum effects are identified by systematic computations for different spin quantum numbers S and by comparing with tight-binding spin-dynamics theory for the classical-spin Kondo model. We demonstrate that, besides the conventional precessional motion and relaxation, the quantum-spin dynamics shows nutation, similar to a spinning top. Opposed to semiclassical theory, however, the nutation is efficiently damped on an extremely short time scale. The effect is explained in the large-S limit as quantum dephasing of the eigenmodes in an emergent two-spin model that is weakly entangled with the bulk of the system. We argue that, apart from the Kondo effect, the damping of nutational motion is essentially the only characteristics of the quantum nature of the spin. Qualitative agreement between quantum and semiclassical spin dynamics is found down to S = 1/2.Introduction.-The paradigmatic system to study the real-time dynamics of a spin-1/2 coupled to a Fermi sea is the Kondo model [1]. It is mainly considered as a generic model for the famous Kondo effect [2], namely screening of the impurity spin by a mesoscopically large number of electrons in a thermal state with temperature below the Kondo temperature T K ∼ exp(−1/Jρ), where J is the strength of the exchange coupling and ρ is the density of states. The Kondo effect is a true quantum effect which originates from the two-fold spin degeneracy and is protected by time-reversal symmetry. Longitudinal spin dynamics, such as the time-dependent Kondo screening, has been studied recently [3,4] by starting from an initial state with a fully polarized spin, which can be prepared with the help of local magnetic field. The longitudinal dynamics is initiated by suddenly switching off the field.

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