Dynamical exchange interaction from time-dependent spin density functional theory

Stamenova, Maria; Sanvito, Stefano

doi:10.1103/physrevb.88.104423

Cited by 7 publications

(10 citation statements)

References 33 publications

(69 reference statements)

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“…In Figure we show a snapshot of this spin precession from our TDDFT GGA simulation. Our results show that with the simple adiabatic GGA approximation we recover the HDVV behavior for the low-frequency dynamics of a spin dimer systems and are consistent with the observation of Stamenova and Sanvito for the same system using the LSDA and a different spin population method and initial conditions . These results provide a justification for the use of the HDVV model for these type of systems from a dynamic point of view.…”

Section: Resultssupporting

confidence: 88%

“…These 2-component KS equations require a noncollinear XC kernel. Developments of XC approximations for noncollinear magnetization were early based on extensions of the LSDA approximation, − and later based on the generalized gradient approximation (GGA) and meta-GGA. ,− For excited-states, noncollinear magnetization has been employed in the linear-response formalism for the evaluation of spin-flip type excitations. − Beyond the linear-response regime, a time-evolution scheme that involves noncollinear magnetization dynamics has been proposed in the framework of Hartree–Fock theory and for the adiabatic LSDA in a basis-free real-space representation, , as well as in an all electron solid-state code based on plane-waves…”

Section: Introductionmentioning

confidence: 99%

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Magnetization Dynamics from Time-Dependent Noncollinear Spin Density Functional Theory Calculations

Peralta

Hod

Scuseria³

2015

J. Chem. Theory Comput.

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A computational scheme, based on a time-dependent extension of noncollinear spin density functional theory, for the simultaneous simulation of charge and magnetization dynamics in molecular systems is presented. We employ a second-order Magnus propagator combined with an efficient predictor-corrector scheme that allows us to treat large molecular systems over long simulation periods. The method is benchmarked against the low-frequency dynamics of the H-He-H molecule where the magnetization dynamics can be modeled by the simple classical magnetization precession of a Heisenberg-Dirac-van Vleck Hamiltonian. Furthermore, the magnetic exchange couplings of the bimetallic complex [Cu(bpy)(H2O)(NO3)2(μ-C2O4)] (BISDOW) are extracted from its low-frequency spin precession dynamics showing good agreement with the coupling obtained from ground state energy differences. Our approach opens the possibility to perform real-time simulation of spin-related phenomena using time-dependent density functional theory in realistic molecular systems.

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Section: Resultssupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Magnetization Dynamics from Time-Dependent Noncollinear Spin Density Functional Theory Calculations

Peralta

Hod

Scuseria³

2015

J. Chem. Theory Comput.

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“…One previous attempt to map the spin dynamics resulting from TDSDFT simulations into the Heisenberg Hamiltonian of Eq. (1) has been based on a simple two-center molecule excited by very short pulsed and local in space magnetic fields [12]. It was noticed that after the extinction of the pulse excitation the two atomic spins, deflected from the collinear ground state to an angle φ, display a precessional motion around the total spin axis with angular velocity given by ω = 4J S cos(φ/2)/h, similarly to a pair of classical Heisenberg-coupled spins.…”

Section: Introductionmentioning

confidence: 99%

Ab initio dynamical exchange interactions in frustrated antiferromagnets

2017

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The ultrafast response to an optical pulse excitation of the spin-spin exchange interaction in transition metal antiferromagnets is studied within the framework of the time-dependent spin-density functional theory. We propose a formulation for the full dynamical exchange interaction, which is nonlocal in space, and it is derived starting from ab initio arguments. Then, we investigate the effect of the laser pulse on the onset of the dynamical process. It is found that we can distinguish two types of excitations, both activated immediately after the action of the laser pulse. While the first one can be associated to a Stoner-like excitation and involves the transfer of spin from one site to another, the second one is related to the ultrafast modification of a Heisenberg-like exchange interaction and can trigger the formation of spin waves in the first few hundred femtoseconds of the time evolution.

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“…The most suitable approach to study the time evolution of spin systems, which is applicable at ultrashort time ( 100 ps) and length ( 1 nm) scales and does not rely on phenomenological parameters, is ab initio spin dynamics (SD). A natural framework for this approach is provided by the extension of density functional theory (DFT) to time domain and noncollinear spins (time-dependent spin DFT, or TD-SDFT), with several practical schemes developed to date [14][15][16][17][18][19]. How-ever, due to computational demands, the system sizes that can be treated with this approach are limited to only a handful of atoms [19].…”

Section: Introductionmentioning

confidence: 99%

“…A natural framework for this approach is provided by the extension of density functional theory (DFT) to time domain and noncollinear spins (time-dependent spin DFT, or TD-SDFT), with several practical schemes developed to date [14][15][16][17][18][19]. How-ever, due to computational demands, the system sizes that can be treated with this approach are limited to only a handful of atoms [19]. In practice, numerical implementations typically rely on approximations.…”

mentioning

confidence: 99%

Spin dynamics of Mn impurities and their bound acceptors in GaAs

2014

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We present results of tight-binding spin-dynamics simulations of individual and pairs of substitutional Mn impurities in GaAs. Our approach is based on the mixed quantum-classical scheme for spin dynamics, with coupled equations of motions for the quantum subsystem, representing the host, and the localized spins of magnetic dopants, which are treated classically. In the case of a single Mn impurity, we calculate explicitly the time evolution of the Mn spin and the spins of nearest-neighbors As atoms, where the acceptor (hole) state introduced by the Mn dopant resides. We relate the characteristic frequencies in the dynamical spectra to the two dominant energy scales of the system, namely the spin-orbit interaction strength and the value of the p-d exchange coupling between the impurity spin and the host carriers. For a pair of Mn impurities, we find signatures of the indirect (carrier-mediated) exchange interaction in the time evolution of the impurity spins. Finally, we examine temporal correlations between the two Mn spins and their dependence on the exchange coupling and spin-orbit interaction strength, as well as on the initial spin-configuration and separation between the impurities. Our results provide insight into the dynamic interaction between localized magnetic impurities in a nano-scaled magnetic-semiconductor sample, in the extremely dilute (solotronics) regime.Comment: 12 pages, 11 figures, journa

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Dynamical exchange interaction from time-dependent spin density functional theory

Cited by 7 publications

References 33 publications

Magnetization Dynamics from Time-Dependent Noncollinear Spin Density Functional Theory Calculations

Magnetization Dynamics from Time-Dependent Noncollinear Spin Density Functional Theory Calculations

Ab initio dynamical exchange interactions in frustrated antiferromagnets

Spin dynamics of Mn impurities and their bound acceptors in GaAs

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