Ultra-fast magnetisation rates within the Landau-Lifshitz-Bloch model

Abstract

The ultra-fast magnetisation relaxation rates during the laser-induced magnetisation process are analyzed in terms of the Landau-Lifshitz-Bloch (LLB) equation for different values of spin $S$. The LLB equation is equivalent in the limit $S\to \infty$ to the atomistic Landau-Lifshitz-Gilbert (LLG) Langevin dynamics and for $S=1/2$ to the M3TM model [B. Koopmans, {\em et al.} Nature Mat. \textbf{9} (2010) 259]. Within the LLB model the ultra-fast demagnetisation time (${\tau }_M$) and the transverse damping (${\alpha }_{\perp }$) are parameterized by the intrinsic coupling-to-the-bath parameter $\lambda$, defined by microscopic spin-flip rate. We show that for the phonon-mediated Elliott-Yafet mechanism, $\lambda$ is proportional to the ratio between the non-equilibrium phonon and electron temperatures. We investigate the influence of the finite spin number and the scattering rate parameter $\lambda$ on the magnetisation relaxation rates. The relation between the fs demagnetisation rate and the LLG damping, provided by the LLB theory, is checked basing on the available experimental data. A good agreement is obtained for Ni, Co and Gd favoring the idea that the same intrinsic scattering process is acting on the femtosecond and nanosecond timescale.

9 pages, 7 figures

References in corpus (9)

• Super-Diffusive Spin-Transport as a Mechanism of Ultrafast Demagnetization
• Identification of the dominant precession damping mechanism in Fe, Co, and Ni by first-principles calculations
• Constrained Monte Carlo Method and Calculation of the Temperature Dependence of Magnetic Anisotropy
• Dynamic approach for micromagnetics close to the Curie temperature
• Hot electron driven enhancement of spin-lattice coupling in 4f ferromagnets observed by femtosecond x-ray magnetic circular dichroism
• Intrinsic and non-local Gilbert damping in polycrystalline nickel studied by Ti:Sapphire laser fs spectroscopy
• Thermal fluctuations and longitudinal relaxation of single-domain magnetic particles at elevated temperatures
• Ultra-fast spin dynamics: the effect of colored noise
• Connecting the timescales in picosecond remagnetization experiments

Cited by in corpus (30)

• Interface-Induced Phenomena in Magnetism
• Atomistic spin model simulations of magnetic nanomaterials
• Perspective: Ultrafast magnetism and THz spintronics
• Speed limit of FePt spin dynamics on femtosecond timescales
• Ab initio theory of electron-phonon mediated ultrafast spin relaxation of laser-excited hot electrons in transition-metal ferromagnets
• Ultrafast dynamical path for the switching of a ferrimagnet after femtosecond heating
• Controlling the Polarity of the Transient Ferromagnetic-Like State in Ferrimagnets
• Quantum Landau-Lifshitz-Bloch equation and its comparison with the classical case
• Boris Computational Spintronics -- High Performance Multi-Mesh Magnetic and Spin Transport Modelling Software
• Phenomenological description of the nonlocal magnetization relaxation in magnonics, spintronics, and domain-wall dynamics
• Modeling ultrafast demagnetization and spin transport: the interplay of spin-polarized electrons and thermal magnons
• Micromagnetic modelling of anisotropic damping in ferromagnet
• Enhancement of ultrafast demagnetization rate and Gilbert damping driven by femtosecond laser-induced spin currents in Fe81Ga19/Ir20Mn80 bilayers
• Emergence of Transient Domain Wall Skyrmions after Ultrafast Demagnetisation
• Insights into ultrafast demagnetization in pseudo-gap half metals
• Ultrafast demagnetization in ferromagnetic materials: Origins and progress
• Exchange scaling of ultrafast angular momentum transfer in 4$f$ antiferromagnets
• Polarisation-dependent single-pulse ultrafast optical switching of an elementary ferromagnet
• Deterministic control of an antiferromagnetic spin arrangement using ultrafast optical excitation
• Magnetization dynamics and damping due to electron-phonon scattering in a ferrimagnetic exchange model
• Element-resolved ultrafast demagnetization rates in ferrimagnetic CoDy
• Ultrafast magnetization dynamics in half-metallic Co${}_2$FeAl Heusler alloy
• Thermodynamically self-consistent non-stochastic micromagnetic model for the ferromagnetic state
• Magnon-driven longitudinal spin Seebeck effect in F|N and N|F|N structures: role of asymmetric in-plane magnetic anisotropy
• Spin-polarized hot electron transport versus spin pumping mediated by local heating
• Analysis of ultrafast magnetization switching dynamics in exchange-coupled ferromagnet-ferrimagnet heterostructures
• Derivation of a time dependent Schrödinger equation as quantum mechanical Landau-Lifshitz-Bloch equation
• Ultrafast reduction in exchange interaction by a laser pulse: Alternative path to femtomagnetism
• Heisenberg representation of nonthermal ultrafast laser excitation of magnetic precessions
• Laser induced phase transition in epitaxial FeRh layers studied by pump-probe valence band photoemission