Spin dynamics of Mn impurities and their bound acceptors in GaAs

Mahani, Mohammad Reza; Pertsova, Anna; Canali, Carlo M.

doi:10.1103/physrevb.90.245406

Cited by 4 publications

(2 citation statements)

References 41 publications

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“…11 of the paper). Calculations carried out on much larger clusters 51 show that show that the qualitative behavior of magnetic anisotropy in Figs. 9 and 11 remains intact as a function of the cluster size, while the value of anisotropy energy saturates to a smaller value without any qualitative change.…”

Section: A Mn Dopants On (110) Gaas Surfacementioning

confidence: 99%

Electronic structure and magnetic properties of Mn and Fe impurities near the GaAs (110) surface

et al. 2014

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Section: A Mn Dopants On (110) Gaas Surfacementioning

confidence: 99%

Electronic structure and magnetic properties of Mn and Fe impurities near the GaAs (110) surface

et al. 2014

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“…As compared to our hybrid theory, much larger time steps and much longer propagation times can be achieved. Opposed to ab initio approaches [16,17,26] we therefore consider a simple one-dimensional non-interacting tight-binding model for the conduction-electron degrees of freedom, i.e., electrons are hopping between the nearest-neighboring sites of a lattice. Within this model approach, systems consisting of about 1000 sites can be treated easily, and we can access sufficiently long time scales to study the spin relaxation.…”

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Spin dynamics and relaxation in the classical-spin Kondo-impurity model beyond the Landau–Lifschitz–Gilbert equation

Sayad

Potthoff

2015

New J. Phys.

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The real-time dynamics of a classical spin in an external magnetic field and local exchange coupled to an extended one-dimensional system of non-interacting conduction electrons is studied numerically. Retardation effects in the coupled electron-spin dynamics are shown to be the source for the relaxation of the spin in the magnetic field. Total energy and spin is conserved in the non-adiabatic process. Approaching the new local ground state is therefore accompanied by the emission of dispersive wave packets of excitations carrying energy and spin and propagating through the lattice with Fermi velocity. While the spin dynamics in the regime of strong exchange coupling J is rather complex and governed by an emergent new time scale, the motion of the spin for weak J is regular and qualitatively well described by the Landau-Lifschitz-Gilbert (LLG) equation. Quantitatively, however, the full quantum-classical hybrid dynamics differs from the LLG approach. This is understood as a breakdown of weak-coupling perturbation theory in J in the course of time. Furthermore, it is shown that the concept of the Gilbert damping parameter is ill-defined for the case of a one-dimensional system. å å a =´++Í t consists of precession terms coupling the spin at site m to an external magnetic field B and, via exchange couplings J mn , to the spins at sites n. Those precession terms typically have a clear atomistic origin, such as the Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction [10-12] which is mediated by the magnetic polarization of conduction electrons. The non-local RKKY couplings J J mn mn 2 c = are given in terms of the elements χ mn of the static conduction-electron spin susceptibility and the local exchange J between the spins and the local magnetic moments of the conduction electrons. Other possibilities comprise direct (Heisenberg) exchange interactions, intra-atomic (Hundʼs) couplings as well as the spin-orbit and other anisotropic interactions. The relaxation term, on the other hand, is often assumed as local, α mn = δ mn α, and represented by purely phenomenological Gilbert damping constant α only. It describes the angular-momentum transfer between the spins and a usually unspecified heat bath.On the atomistic level, the Gilbert damping must be seen as originating from microscopic couplings of the spins to the conduction-electron system (as well as to lattice degrees of freedom which, however, will not be considered here). There are numerous studies where the damping constant, or tensor, α has been computed numerically from a more fundamental model including electron degrees of freedom explicitly [13][14][15] or even from first principles [16][17][18][19][20][21]. All these studies rely on two, partially related, assumptions: (i) the spin-electron coupling J is weak and can be treated perturbatively to lowest order, i.e., the Kubo formula or linear-response theory is employed. (ii) The classical spin dynamics is slow as compared to the electron dynamics. These assumptions appear as well justified but they are also nec...

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