Signatures of relativistic spin-light coupling in magneto-optical pump-probe experiments

Mondal, Ritwik; Berritta, Marco; Oppeneer, Peter M.

doi:10.1088/1361-648x/aa68ea

Cited by 15 publications

(10 citation statements)

References 84 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The first two terms on the right-hand side have the usual physical interpretations. The third term defines the optical spin-orbit torque on the magnetization, related to a relativistic contribution to the inverse Faraday effect, where the optomagnetic field is proportional to E ×E i.e., intensity for a general electric field [93]. The fourth term is the Berger [8] adiabatic STT as has already been pointed out before, and finally, the last two terms are the SOTs.…”

Section: Complete Magnetization Dynamicsmentioning

confidence: 91%

See 1 more Smart Citation

Unified theory of magnetization dynamics with relativistic and nonrelativistic spin torques

2018

Self Cite

View full text Add to dashboard Cite

Spin torques play a crucial role in operative properties of modern spintronic devices. To study current-driven magnetization dynamics, spin-torque terms providing the action of spin-polarized currents have previously often been added in a phenomenological way to the Landau-Lifshitz-Gilbert equation describing the local spin dynamics, yet without derivation from fundamental principles. Here, starting from the Dirac-Kohn-Sham theory and incorporating nonlocal spin transport we rigorously derive the various spin-torque terms that appear in current-driven magnetization dynamics. In particular we obtain an extended magnetization dynamics equation that precisely contains the nonrelativistic adiabatic and relativistic nonadiabatic spin-transfer torques (STTs) of the Berger and Zhang-Li forms as well as relativistic spin-orbit torques (SOTs). We derive in addition a previously unnoticed relativistic spin-torque term and moreover show that the various obtained spin-torque terms do not appear in the same mathematical form in both the Landau-Lifshitz and Landau-Lifshitz-Gilbert equations of spin dynamics.

show abstract

Section: Complete Magnetization Dynamicsmentioning

confidence: 91%

“…where we have introduced the optomagnetic field that can be written as B opt = e 2mc 2 (E ext × A) [44,82,93]. The ensuing dynamics essentially defines the optical spin-orbit torque acting on the local magnetization.…”

Section: B Relativistic Magnetization Dynamicsmentioning

confidence: 99%

Unified theory of magnetization dynamics with relativistic and nonrelativistic spin torques

2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…The Hamiltonian in Eq. ( 14) has been used in calculating the general spin dynamics with the Pauli spin operator [7,8,22,24,29,30,[35][36][37][38][39][40]. We comment that the calculated spin dynamics could explain the precession, spin relaxation of Gilbert type and even nutation dynamics of a single spin [37].…”

Section: Relativistic Hamiltoniansmentioning

confidence: 99%

Dynamics of the relativistic electron spin in an electromagnetic field

Mondal,

Oppeneer

2020

Preprint

Self Cite

View full text Add to dashboard Cite

A relativistic spin operator cannot be uniquely defined within relativistic quantum mechanics. Previously, different proper relativistic spin operators have been proposed, such as spin operators of the Foldy-Wouthuysen and Pryce type, that both commute with the free-particle Dirac Hamiltonian and represent constants of motion. Here we consider the dynamics of a relativistic electron spin in an external electromagnetic field. We use two different Hamiltonians to derive the corresponding spin dynamics. These two are: (a) the Dirac Hamiltonian in presence of an external field, (b) the semirelativistic expansion of the same. Considering the Foldy-Wouthuysen and Pryce spin operators we show that these lead to different spin dynamics in an external electromagnetic field, which offers possibilities to distinguish their action. We find that the dynamics of both spin operators involve spindependent and spin-independent terms, however, the Foldy-Wouthuysen spin dynamics additionally accounts for the relativistic particle-antiparticle coupling. We conclude that the Pryce spin operator provides a suitable description of the relativistic spin dynamics in a weak-to-intermediate external field, whereas the Foldy-Wouthuysen spin operator is more suitable in the strong field regime.

show abstract

“…It avoids problems caused by material heating, which limits a repetition frequency due to a required cooling time and a recording density due to heat diffusion. Therefore, the demonstration of the UIFE, in which magnetic oscillations in canted antiferromagnet DyFeO 3 were induced by circularly polarized ultrashort laser pulses [5], motivated intensive theoretical [6][7][8][9][10][11][12][13][14][15][16][17][18] and experimental [19][20][21][22][23] studies of this process. A significant progress in development of techniques of ultrafast spin control using femtosecond laser pulses based on the UIFE was demonstrated in recent years [22,[24][25][26][27][28][29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Heisenberg representation of nonthermal ultrafast laser excitation of magnetic precessions

Popova-Gorelova,

Bringer,

Blügel

2021

Preprint

View full text Add to dashboard Cite

We derive the Heisenberg representation of the ultrafast inverse Faraday effect that provides the time evolution of magnetic vectors of a magnetic system during its interaction with a laser pulse. We obtain a time-dependent effective magnetic operator acting in the Hilbert space of the total angular momentum that describes a process of nonthermal excitation of magnetic precessions in an electronic system by a circularly polarized laser pulse. The magnetic operator separates the effect of the laser pulse on the magnetic system from other magnetic interactions. The effective magnetic operator provides the equations of motion of magnetic vectors during the excitation by the laser. We show that magnetization dynamics calculated with these equations is equivalent to magnetization dynamics calculated with the time-dependent Schrödinger equation, which takes into account the interaction of an electronic system with the electric field of light. We model and compare laser-induced precessions of magnetic sublattices of an easy-plane and an easy-axis antiferromagnetic systems. Using these models, we show how the ultrafast inverse Faraday effect induces a net magnetic moment in antiferromagnets and demonstrate that a crystal field environment and the exchange interaction play essential roles for laser-induced magnetization dynamics even during the action of a pump pulse. Using our approach, we show that light-induced precessions can start even during the action of the pump pulse with a duration several tens times shorter than the period of induced precessions and affect the position of magnetic vectors after the action of the pump pulse.

show abstract

Signatures of relativistic spin-light coupling in magneto-optical pump-probe experiments

Cited by 15 publications

References 84 publications

Unified theory of magnetization dynamics with relativistic and nonrelativistic spin torques

Unified theory of magnetization dynamics with relativistic and nonrelativistic spin torques

Dynamics of the relativistic electron spin in an electromagnetic field

Heisenberg representation of nonthermal ultrafast laser excitation of magnetic precessions

Contact Info

Product

Resources

About