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2003-09-11
Theory of Current-Induced Magnetization Precession
We solve appropriate drift-diffusion and Landau-Lifshitz-Gilbert equations to demonstrate that unpolarized current flow from a non-magnet into a ferromagnet can produce a precession-type instability of the magnetization. The fundamental origin of the instability is the difference in conductivity between majority spins ...
0309289v1
2005-07-20
All-optical probe of precessional magnetization dynamics in exchange biased NiFe/FeMn bilayers
An internal anisotropy pulse field is launched by an 8.3 ps short laser excitation, which triggers precessional magnetization dynamics of a polycrystalline NiFe/FeMn exchange bias system on the picosecond timescale. Due to the excitation the unidirectional anisotropy and, thus, the exchange coupling across the interfac...
0507475v1
2008-11-25
The quantum-mechanical basis of an extended Landau-Lifshitz-Gilbert equation for a current-carrying ferromagnetic wire
An extended Landau-Lifshitz-Gilbert (LLG) equation is introduced to describe the dynamics of inhomogeneous magnetization in a current-carrying wire. The coefficients of all the terms in this equation are calculated quantum-mechanically for a simple model which includes impurity scattering. This is done by comparing the...
0811.4118v1
2009-05-28
Hydrodynamic theory of coupled current and magnetization dynamics in spin-textured ferromagnets
We develop the hydrodynamical theory of collinear spin currents coupled to magnetization dynamics in metallic ferromagnets. The collective spin density couples to the spin current through a U(1) Berry-phase gauge field determined by the local texture and dynamics of the magnetization. We determine phenomenologically th...
0905.4544v2
2010-11-26
Dependence of nonlocal Gilbert damping on the ferromagnetic layer type in FM/Cu/Pt heterostructures
We have measured the size effect in nonlocal Gilbert relaxation rate in FM(t$_{FM}$) / Cu (5nm) [/ Pt (2nm)] / Al(2nm) heterostructures, FM = \{ Ni$_{81}$Fe$_{19}$, Co$_{60}$Fe$_{20}$B$_{20}$, pure Co\}. Common behavior is observed for three FM layers, where the additional relaxation obeys both a strict inverse power l...
1011.5868v1
2012-06-21
Fast domain wall propagation in uniaxial nanowires with transverse fields
Under a magnetic field along its axis, domain wall motion in a uniaxial nanowire is much slower than in the fully anisotropic case, typically by several orders of magnitude (the square of the dimensionless Gilbert damping parameter). However, with the addition of a magnetic field transverse to the wire, this behaviour ...
1206.4819v2
2013-03-05
Angle-Dependent Spin-Wave Resonance Spectroscopy of (Ga,Mn)As Films
A modeling approach for standing spin-wave resonances based on a finite-difference formulation of the Landau-Lifshitz-Gilbert equation is presented. In contrast to a previous study [Bihler et al., Phys. Rev. B 79, 045205 (2009)], this formalism accounts for elliptical magnetization precession and magnetic properties ar...
1303.1192v1
2013-04-26
Landau-Lifshitz theory of the longitudinal spin Seebeck effect
Thermal-bias-induced spin angular momentum transfer between a paramagnetic metal and ferromagnetic insulator is studied theoretically based on the stochastic Landau-Lifshitz-Gilbert (LLG) phenomenology. Magnons in the ferromagnet establish a nonequilibrium steady state by equilibrating with phonons via bulk Gilbert dam...
1304.7295v2
2013-09-21
Patterns formation in axially symmetric Landau-Lifshitz-Gilbert-Slonczewski equations
The Landau-Lifshitz-Gilbert-Slonczewski equation describes magnetization dynamics in the presence of an applied field and a spin polarized current. In the case of axial symmetry and with focus on one space dimension, we investigate the emergence of space-time patterns in the form of wavetrains and coherent structures, ...
1309.5523v4
2014-02-27
On the longitudinal spin current induced by a temperature gradient in a ferromagnetic insulator
Based on the solution of the stochastic Landau-Lifshitz-Gilbert equation discretized for a ferromagnetic chain subject to a uniform temperature gradient, we present a detailed numerical study of the spin dynamics with a focus particularly on finite-size effects. We calculate and analyze the net longitudinal spin curren...
1402.6899v1
2015-01-19
Effect of Exchange Interaction on Magnetic Thermal Fluctuation and Spin Susceptibility
The expression of the thermal fluctuation parameter in the stochastic Landau-Lifshitz-Gilbert equation has been derived from a fundamental quantum theory of spins and phonons, in which the exchange interaction between nearest atoms has been included. Our studies show that the thermal fluctuation decreases exponentially...
1501.04503v2
2015-07-23
Nanomagnet coupled to quantum spin Hall edge: An adiabatic quantum motor
The precessing magnetization of a magnetic islands coupled to a quantum spin Hall edge pumps charge along the edge. Conversely, a bias voltage applied to the edge makes the magnetization precess. We point out that this device realizes an adiabatic quantum motor and discuss the efficiency of its operation based on a sca...
1507.06505v2
2017-03-28
Temperature dependent magnetic damping of yttrium iron garnet spheres
We investigate the temperature dependent microwave absorption spectrum of an yttrium iron garnet sphere as a function of temperature (5 K to 300 K) and frequency (3 GHz to 43.5 GHz). At temperatures above 100 K, the magnetic resonance linewidth increases linearly with temperature and shows a Gilbert-like linear frequen...
1703.09444v2
2017-12-10
Magnetic field gradient driven dynamics of isolated skyrmions and antiskyrmions in frustrated magnets
The study of skyrmion/antiskyrmion motion in magnetic materials is very important in particular for the spintronics applications. In this work, we study the dynamics of isolated skyrmions and antiskyrmions in frustrated magnets driven by magnetic field gradient, using the Landau-Lifshitz-Gilbert simulations on the frus...
1712.03550v1
2018-02-28
Roles of chiral renormalization on magnetization dynamics in chiral magnets
In metallic ferromagnets, the interaction between local magnetic moments and conduction electrons renormalizes parameters of the Landau-Lifshitz-Gilbert equation such as the gyromagnetic ratio and the Gilbert damping, and makes them dependent on the magnetic configurations. Although the effects of the renormalization f...
1803.00017v2
2018-12-20
Laser Controlled Spin Dynamics of Ferromagnetic Thin Film from Femtosecond to Nanosecond Timescale
Laser induced modulation of the magnetization dynamics occurring over various time-scales have been unified here for a Ni80Fe20 thin film excited by amplified femtosecond laser pulses. The weak correlation between demagnetization time and pump fluence with substantial enhancement in remagnetization time is demonstrated...
1812.08404v1
2019-03-13
Higher-order linearly implicit full discretization of the Landau--Lifshitz--Gilbert equation
For the Landau--Lifshitz--Gilbert (LLG) equation of micromagnetics we study linearly implicit backward difference formula (BDF) time discretizations up to order $5$ combined with higher-order non-conforming finite element space discretizations, which are based on the weak formulation due to Alouges but use approximate ...
1903.05415v2
2019-12-01
Coarse-graining in micromagnetic simulations of dynamic hysteresis loops
Micromagnetic simulations based on the stochastic Landau-Lifshitz-Gilbert equation are used to calculate dynamic magnetic hysteresis loops relevant to magnetic hyperthermia. With the goal to effectively simulate room-temperature loops for large iron-oxide-based systems at relatively slow sweep rates on the order of 1 O...
1912.00310v3
2020-02-17
Self-similar shrinkers of the one-dimensional Landau-Lifshitz-Gilbert equation
The main purpose of this paper is the analytical study of self-shrinker solutions of the one-dimensional Landau-Lifshitz-Gilbert equation (LLG), a model describing the dynamics for the spin in ferromagnetic materials. We show that there is a unique smooth family of backward self-similar solutions to the LLG equation, u...
2002.06858v2
2021-02-20
Fast magnetization reversal of a magnetic nanoparticle induced by cosine chirp microwave field pulse
We investigate the magnetization reversal of single-domain magnetic nanoparticle driven by the circularly polarized cosine chirp microwave pulse (CCMP). The numerical findings, based on the Landau-Lifshitz-Gilbert equation, reveal that the CCMP is by itself capable of driving fast and energy-efficient magnetization rev...
2102.10394v2
2021-07-24
Electron-Phonon Scattering governs both Ultrafast and Precessional Magnetization Dynamics in Co-Fe Alloys
Recent investigations have advanced the understanding of how structure-property relationships in ferromagnetic metal alloys affect the magnetization dynamics on nanosecond time-scales. A similar understanding for magnetization dynamics on femto- to pico-second time-scales does not yet exist. To address this, we perform...
2107.11699v1
2022-09-07
Convergence analysis of an implicit finite difference method for the inertial Landau-Lifshitz-Gilbert equation
The Landau-Lifshitz-Gilbert (LLG) equation is a widely used model for fast magnetization dynamics in ferromagnetic materials. Recently, the inertial LLG equation, which contains an inertial term, has been proposed to capture the ultra-fast magnetization dynamics at the sub-picosecond timescale. Mathematically, this gen...
2209.02914v2
2022-09-16
Pseudo-PT symmetric Dirac equation : effect of a new mean spin angular momentum operator on Gilbert damping
The pseudo-PT symmetric Dirac equation is proposed and analyzed by using a non-unitary Foldy-Wouthuysen transformations. A new spin operator PT symmetric expectation value (called the mean spin operator) for an electron interacting with a time-dependent electromagnetic field is obtained. We show that spin magnetization...
2209.07908v1
2022-11-15
Nonlinear sub-switching regime of magnetization dynamics in photo-magnetic garnets
We analyze, both experimentally and numerically, the nonlinear regime of the photo-induced coherent magnetization dynamics in cobalt-doped yttrium iron garnet films. Photo-magnetic excitation with femtosecond laser pulses reveals a strongly nonlinear response of the spin subsystem with a significant increase of the eff...
2211.08048v2
2023-08-16
Discovery and regulation of chiral magnetic solitons: Exact solution from Landau-Lifshitz-Gilbert equation
The Landau-Lifshitz-Gilbert (LLG) equation has emerged as a fundamental and indispensable framework within the realm of magnetism. However, solving the LLG equation, encompassing full nonlinearity amidst intricate complexities, presents formidable challenges. In this context, we develop a precise mapping through geomet...
2308.08331v1
2002-12-05
Dynamic stiffness of spin valves
The dynamics of the magnetic order parameters of ferromagnet/normal-metal/ferromagnet spin valves and isolated ferromagnets may be very different. We investigate the role of the nonequilibrium spin-current exchange between the ferromagnets in the magnetization precession and switching. We find a (low-temperature) criti...
0212130v2
2005-01-13
Magnetization noise in magnetoelectronic nanostructures
By scattering theory we show that spin current noise in normal electric conductors in contact with nanoscale ferromagnets increases the magnetization noise by means of a fluctuating spin-transfer torque. Johnson-Nyquist noise in the spin current is related to the increased Gilbert damping due to spin pumping, in accord...
0501318v1
2005-01-27
Current-induced macrospin vs spin-wave excitations in spin valves
The mode dependence of current-induced magnetic excitations in spin valves is studied theoretically. The torque exerted on the magnetization by transverse spin currents as well as the Gilbert damping constant are found to depend strongly on the wave length of the excitation (spin wave). Analytic expressions are present...
0501672v3
2006-05-08
Microscopic Calculation of Spin Torques in Disordered Ferromagnets
Effects of conduction electrons on magnetization dynamics, represented by spin torques, are calculated microscopically in the first order in spatial gradient and time derivative of magnetization. Special attention is paid to the so-called $\beta$-term and the Gilbert damping, $\alpha$, in the presence of electrons' spi...
0605186v1
2006-11-27
Microscopic Calculation of Spin Torques and Forces
Spin torques, that is, effects of conduction electrons on magnetization dynamics, are calculated microscopically in the first order in spatial gradient and time derivative of magnetization. Special attention is paid to the so-called \beta-term and the Gilbert damping, \alpha, in the presence of electrons' spin-relaxati...
0611669v1
2007-10-15
Ferromagnetic resonance study of polycrystalline Fe_{1-x}V_x alloy thin films
Ferromagnetic resonance has been used to study the magnetic properties and magnetization dynamics of polycrystalline Fe$_{1-x}$V$_{x}$ alloy films with $0\leq x < 0.7$. Films were produced by co-sputtering from separate Fe and V targets, leading to a composition gradient across a Si substrate. FMR studies were conducte...
0710.2826v2
2008-10-25
The domain wall spin torque-meter
We report the direct measurement of the non-adiabatic component of the spin-torque in domain walls. Our method is independent of both the pinning of the domain wall in the wire as well as of the Gilbert damping parameter. We demonstrate that the ratio between the non-adiabatic and the adiabatic components can be as hig...
0810.4633v1
2008-12-03
Observation of ferromagnetic resonance in strontium ruthenate (SrRuO3)
We report the observation of ferromagnetic resonance (FMR) in SrRuO3 using the time-resolved magneto-optical Kerr effect. The FMR oscillations in the time-domain appear in response to a sudden, optically induced change in the direction of easy-axis anistropy. The high FMR frequency, 250 GHz, and large Gilbert damping p...
0812.0832v1
2011-02-26
Dynamics of Skyrmion Crystals in Metallic Thin Films
We study the collective dynamics of the Skyrmion crystal (SkX) in thin films of ferromagnetic metals resulting from the nontrivial Skyrmion topology. We show that the current-driven motion of the crystal reduces the topological Hall effect and the Skyrmion trajectories bend away from the direction of the electric curre...
1102.5384v2
2011-04-15
Lagrangian approach and dissipative magnetic systems
A Lagrangian is introduced which includes the coupling between magnetic moments $\mathbf{m}$ and the degrees of freedom $\boldsymbol{\sigma}$ of a reservoir. In case the system-reservoir coupling breaks the time reversal symmetry the magnetic moments perform a damped precession around an effective field which is self-o...
1104.3002v1
2011-07-04
Minimization of the Switching Time of a Synthetic Free Layer in Thermally Assisted Spin Torque Switching
We theoretically studied the thermally assisted spin torque switching of a synthetic free layer and showed that the switching time is minimized if the condition H_J=|H_s|/(2 alpha) is satisfied, where H_J, H_s and alpha are the coupling field of two ferromagnetic layers, the amplitude of the spin torque, and the Gilber...
1107.0753v2
2012-09-14
Skyrmion Dynamics in Multiferroic Insulator
Recent discovery of Skyrmion crystal phase in insulating multiferroic compound Cu$_2$OSeO$_3$ calls for new ways and ideas to manipulate the Skyrmions in the absence of spin transfer torque from the conduction electrons. It is shown here that the position-dependent electric field, pointed along the direction of the ave...
1209.3120v1
2013-03-12
Thermally excited spin waves in a nano-structure: thermal gradient vs. constant temperature
Using micromagnetic simulations, we have investigated spin dynamics in a nanostructure in the presence of thermal fluctuations. In particular, we have studied the effects of a uniform temperature and of a uniform thermal gradient. In both cases, the stochastic field leads to an increase of the precession angle of the m...
1303.2895v1
2013-07-29
Theoretical Study of Spin-Torque Oscillator with Perpendicularly Magnetized Free Layer
The magnetization dynamics of spin torque oscillator (STO) consisting of a perpendicularly magnetized free layer and an in-plane magnetized pinned layer was studied by solving the Landau-Lifshitz-Gilbert equation. We derived the analytical formula of the relation between the current and the oscillation frequency of the...
1307.7427v1
2014-06-10
Influence of Ta insertions on the magnetic properties of MgO/CoFeB/MgO films probed by ferromagnetic resonance
We show by vector network analyzer ferromagnetic resonance measurements that low Gilbert damping {\alpha} down to 0.006 can be achieved in perpendicularly magnetized MgO/CoFeB/MgO thin films with ultra-thin insertions of Ta in the CoFeB layer. While increasing the number of Ta insertions allows thicker CoFeB layers to ...
1406.2491v2
2014-09-24
Dissipationless Multiferroic Magnonics
We propose that the magnetoelectric effect in multiferroic insulators with coplanar antiferromagnetic spiral order, such as BiFeO$_{3}$, enables electrically controlled dissipationless magnonics. Applying an oscillating electric field in these materials with frequency as low as household frequency can activate Goldston...
1409.6900v2
2015-02-09
Large amplitude oscillation of magnetization in spin-torque oscillator stabilized by field-like torque
Oscillation frequency of spin torque oscillator with a perpendicularly magnetized free layer and an in-plane magnetized pinned layer is theoretically investigated by taking into account the field-like torque. It is shown that the field-like torque plays an important role in finding the balance between the energy suppli...
1502.02699v1
2015-06-02
Current-Driven Motion of Magnetic Domain Wall with Many Bloch Lines
The current-driven motion of a domain wall (DW) in a ferromagnet with many Bloch lines (BLs) via the spin transfer torque is studied theoretically. It is found that the motion of BLs changes the current-velocity ($j$-$v$) characteristic dramatically. Especially, the critical current density to overcome the pinning forc...
1506.00723v1
2015-07-24
Boosting Domain Wall Propagation by Notches
We report a counter-intuitive finding that notches in an otherwise homogeneous magnetic nanowire can boost current-induced domain wall (DW) propagation. DW motion in notch-modulated wires can be classified into three phases: 1) A DW is pinned around a notch when the current density is below the depinning current densit...
1507.06748v1
2016-01-23
Nonlinear magnetization dynamics of antiferromagnetic spin resonance induced by intense terahertz magnetic field
We report on the nonlinear magnetization dynamics of a HoFeO3 crystal induced by a strong terahertz magnetic field resonantly enhanced with a split ring resonator and measured with magneto-optical Kerr effect microscopy. The terahertz magnetic field induces a large change (~40%) in the spontaneous magnetization. The fr...
1601.06213v1
2017-08-11
Gradient expansion formalism for generic spin torques
We propose a new quantum-mechanical formalism to calculate spin torques based on the gradient expansion, which naturally involves spacetime gradients of the magnetization and electromagnetic fields. We have no assumption in the small-amplitude formalism or no difficulty in the SU($2$) gauge transformation formalism. As...
1708.03424v1
2019-06-03
Magnon-phonon interactions in magnetic insulators
We address the theory of magnon-phonon interactions and compute the corresponding quasi-particle and transport lifetimes in magnetic insulators with focus on yttrium iron garnet at intermediate temperatures from anisotropy- and exchange-mediated magnon-phonon interactions, the latter being derived from the volume depen...
1906.01042v1
2019-09-17
Microwave induced tunable subharmonic steps in superconductor-ferromagnet-superconductor Josephson junction
We investigate the coupling between ferromagnet and superconducting phase dynamics in superconductor-ferromagnet-superconductor Josephson junction. The current-voltage characteristics of the junction demonstrate a pattern of subharmonic current steps which forms a devil's staircase structure. We show that a width of th...
1909.08004v1
2019-09-19
Magnetization dynamics of the compensated ferrimagnet $Mn_{2}Ru_{x}Ga$
Here we study both static and time-resolved dynamic magnetic properties of the compensated ferrimagnet from room temperature down to 10K, thus crossing the magnetic compensation temperature $T_{M}$. The behaviour is analysed with a model of a simple collinear ferrimagnet with uniaxial anisotropy and site-specific gyrom...
1909.09085v1
2019-11-28
Transport properties of spin superfluids: comparing easy-plane ferro- and antiferromagnets
We present a study on spin-superfluid transport based on an atomistic, classical spin model. Easy-plane ferro- as well as antiferromagnets are considered, which allows for a direct comparison of these two material classes based on the same model assumptions. We find a spin-superfluid transport which is robust against v...
1911.12786v1
2020-01-17
Fermi Level Controlled Ultrafast Demagnetization Mechanism in Half-Metallic Heusler Alloy
The electronic band structure-controlled ultrafast demagnetization mechanism in Co2FexMn1-xSi Heusler alloy is underpinned by systematic variation of composition. We find the spin-flip scattering rate controlled by spin density of states at Fermi level is responsible for non-monotonic variation of ultrafast demagnetiza...
2001.06217v1
2020-04-17
Collective coordinate study of spin wave emission from dynamic domain wall
We study theoretically the spin wave emission from a moving domain wall in a ferromagnet. Introducing a deformation mode describing a modulation of the wall thickness in the collective coordinate description, we show that thickness variation couples to the spin wave linearly and induces spin wave emission. The dominant...
2004.08082v1
2021-03-10
Anisotropic superconducting spin transport at magnetic interfaces
We present a theoretical investigation of anisotropic superconducting spin transport at a magnetic interface between a p-wave superconductor and a ferromagnetic insulator. Our formulation describes the ferromagnetic resonance modulations due to spin current generation depending on spin-triplet Cooper pair, including th...
2103.05871v3
2022-01-16
Ferromagnetic resonance modulation in $d$-wave superconductor/ferromagnetic insulator bilayer systems
We investigate ferromagnetic resonance (FMR) modulation in $d$-wave superconductor (SC)/ferromagnetic insulator (FI) bilayer systems theoretically. The modulation of the Gilbert damping in these systems reflects the existence of nodes in the $d$-wave SC and shows power-law decay characteristics within the low-temperatu...
2201.06060v2
2022-09-28
Unidirectional magnetic coupling
We show that interlayer Dzyaloshinskii-Moriya interaction in combination with non-local Gilbert damping gives rise to unidirectional magnetic coupling. That is, the coupling between two magnetic layers -- say the left and right layer -- is such that dynamics of the left layer leads to dynamics of the right layer, but n...
2209.14179v1
2023-08-11
Dynamical Majorana Ising spin response in a topological superconductor-magnet hybrid by microwave irradiation
We study a dynamical spin response of surface Majorana modes in a topological superconductor-magnet hybrid under microwave irradiation. We find a method to toggle between dissipative and non-dissipative Majorana Ising spin dynamics by adjusting the external magnetic field angle and the microwave frequency. This reflect...
2308.05955v2
2006-10-04
On the dynamics of spin systems in the Landau-Lifshitz theory
In the framework of the Landau-Lifshitz equations without any dissipation (an approximation which may also be helpful for finite but weak Gilbert damping), with all interactions included, for general ground states, geometries and domain structures, and many types of effective fields the dynamics of the spin precession ...
0610122v4
2016-04-26
First principles studies of the Gilbert damping and exchange interactions for half-metallic Heuslers alloys
Heusler alloys have been intensively studied due to the wide variety of properties that they exhibit. One of these properties is of particular interest for technological applications, i.e. the fact that some Heusler alloys are half-metallic. In the following, a systematic study of the magnetic properties of three diffe...
1604.07552v1
2016-12-21
Spin Pumping, Dissipation, and Direct and Alternating Inverse Spin Hall Effects in Magnetic Insulator-Normal Metal Bilayers
We theoretically consider the spin-wave mode- and wavelength-dependent enhancement of the Gilbert damping in magnetic insulator--normal metal bilayers due to spin pumping as well as the enhancement's relation to direct and alternating inverse spin Hall voltages in the normal metal. In the long-wavelength limit, includi...
1612.07020v2
2019-10-29
Perpendicular magnetic anisotropy in Pt/Co-based full Heusler alloy/MgO thin films structures
Perpendicular magnetic anisotropy (PMA) in ultrathin magnetic structures is a key ingredient for the development of electrically controlled spintronic devices. Due to their relatively large spin-polarization, high Curie temperature and low Gilbert damping the Co-based full Heusler alloys are of special importance from ...
1910.13107v1
2020-10-15
Spin injection characteristics of Py/graphene/Pt by gigahertz and terahertz magnetization dynamics driven by femtosecond laser pulse
Spin transport characteristics of graphene has been extensively studied so far. The spin transport along c-axis is however reported by rather limited number of papers. We have studied spin transport characteristics through graphene along c-axis with permalloy(Py)/graphene(Gr)/Pt by gigahertz (GHz) and terahertz (THz) m...
2010.07694v1
2021-03-17
Spin injection efficiency at metallic interfaces probed by THz emission spectroscopy
Terahertz (THz) spin-to-charge conversion has become an increasingly important process for THz pulse generation and as a tool to probe ultrafast spin interactions at magnetic interfaces. However, its relation to traditional, steady state, ferromagnetic resonance techniques is poorly understood. Here we investigate nano...
2103.09557v1
2021-09-13
Control of magnetization dynamics by substrate orientation in YIG thin films
Yttrium Iron Garnet (YIG) and bismuth (Bi) substituted YIG (Bi0.1Y2.9Fe5O12, BYG) films are grown in-situ on single crystalline Gadolinium Gallium Garnet (GGG) substrates [with (100) and (111) orientations] using pulsed laser deposition (PLD) technique. As the orientation of the Bi-YIG film changes from (100) to (111),...
2109.05901v1
2022-06-06
Probing spin dynamics of ultra-thin van der Waals magnets via photon-magnon coupling
Layered van der Waals (vdW) magnets can maintain a magnetic order even down to the single-layer regime and hold promise for integrated spintronic devices. While the magnetic ground state of vdW magnets was extensively studied, key parameters of spin dynamics, like the Gilbert damping, crucial for designing ultra-fast s...
2206.02460v2
2022-09-01
Growth parameters of Bi0.1Y2.9Fe5O12 thin films for high frequency applications
The growth and characterization of Bismuth (Bi) substituted YIG (Bi-YIG, Bi0.1Y2.9Fe5O12) thin films are reported. Pulsed laser deposited (PLD) films with thicknesses ranging from 20 to 150 nm were grown on Gadolinium Gallium Garnet substrates. Two substrate orientations of (100) and (111) were considered. The enhanced...
2209.00558v1
2023-03-13
Experimental investigation of the effect of topological insulator on the magnetization dynamics of ferromagnetic metal: $BiSbTe_{1.5}Se_{1.5}$ and $Ni_{80}Fe_{20}$ heterostructure
We have studied ferromagnetic metal/topological insulator bilayer system to understand magnetization dynamics of ferromagnetic metal (FM) in contact with a topological insulator (TI). At magnetic resonance condition, the precessing magnetization in the metallic ferromagnet ($Ni_{80}Fe_{20}$) injects spin current into t...
2303.07025v2
2017-02-27
Current Induced Damping of Nanosized Quantum Moments in the Presence of Spin-Orbit Interaction
Motivated by the need to understand current-induced magnetization dynamics at the nanoscale, we have developed a formalism, within the framework of Keldysh Green function approach, to study the current-induced dynamics of a ferromagnetic (FM) nanoisland overlayer on a spin-orbit-coupling (SOC) Rashba plane. In contrast...
1702.08408v2
2018-12-18
Thermal gradient driven domain wall dynamics
The issue of whether a thermal gradient acts like a magnetic field or an electric current in the domain wall (DW) dynamics is investigated. Broadly speaking, magnetization control knobs can be classified as energy-driving or angular-momentum driving forces. DW propagation driven by a static magnetic field is the best-k...
1812.07244v2
2021-06-16
Spin-Torque-driven Terahertz Auto Oscillations in Non-Collinear Coplanar Antiferromagnets
We theoretically and numerically study the terahertz auto oscillations in thin-film metallic non-collinear coplanar antiferromagnets (AFMs), such as $\mathrm{Mn_{3}Sn}$ and $\mathrm{Mn_{3}Ir}$, under the effect of anti-damping spin-torque with spin polarization perpendicular to the plane of the film. To obtain the orde...
2106.08528v2
2023-01-30
Investigation of Ultrafast Demagnetization and Gilbert Damping and their Correlation in Different Ferromagnetic Thin Films Grown Under Identical Conditions
Following the demonstration of laser-induced ultrafast demagnetization in ferromagnetic nickel, several theoretical and phenomenological propositions have sought to uncover its underlying physics. In this work we revisit the three temperature model (3TM) and the microscopic three temperature model (M3TM) to perform a c...
2301.12797v1
2001-03-30
Thermal magnetization fluctuations in thin films and a new physical form for magnetization damping
The effect of thermal fluctuations on a thin film magnetoresistive element has been calculated. The technique involves adding to the basic spin dynamics a general form of interaction with a thermal bath. For a general anisotropic magnetic system the resulting equation can be written as a Langevin equation for a harmoni...
0103624v3
2004-02-03
First-principles study of magnetization relaxation enhancement and spin-transfer in thin magnetic films
The interface-induced magnetization damping of thin ferromagnetic films in contact with normal-metal layers is calculated from first principles for clean and disordered Fe/Au and Co/Cu interfaces. Interference effects arising from coherent scattering turn out to be very small, consistent with a very small magnetic cohe...
0402088v2
2005-02-28
Magnetization dynamics of two interacting spins in an external magnetic field
The longitudinal relaxation time of the magnetization of a system of two exchange coupled spins subjected to a strong magnetic field is calculated exactly by averaging the stochastic Gilbert-Landau-Lifshitz equation for the magnetization, i.e., the Langevin equation of the process, over its realizations so reducing the...
0502661v2
2007-06-28
Coherent Magnetization Precession in GaMnAs induced by Ultrafast Optical Excitation
We use femtosecond optical pulses to induce, control and monitor magnetization precession in ferromagnetic Ga0.965Mn0.035As. At temperatures below ~40 K we observe coherent oscillations of the local Mn spins, triggered by an ultrafast photoinduced reorientation of the in-plane easy axis. The amplitude saturation of the...
0706.4270v2
2008-02-14
Light-induced magnetization precession in GaMnAs
We report dynamics of the transient polar Kerr rotation (KR) and of the transient reflectivity induced by femtosecond laser pulses in ferromagnetic (Ga,Mn)As with no external magnetic field applied. It is shown that the measured KR signal consist of several different contributions, among which only the oscillatory sign...
0802.2043v2
2008-09-17
Spin-transfer torque induced reversal in magnetic domains
Using the complex stereographic variable representation for the macrospin, from a study of the nonlinear dynamics underlying the generalized Landau-Lifshitz(LL) equation with Gilbert damping, we show that the spin-transfer torque is effectively equivalent to an applied magnetic field. We study the macrospin switching o...
0809.2910v1
2009-12-30
Spin torque and critical currents for magnetic vortex nano-oscillator in nanopillars
We calculated the main dynamic parameters of the spin polarized current induced magnetic vortex oscillations in nanopillars, such as the range of current density, where a vortex steady oscillations exist, the oscillation frequency and orbit radius. We accounted for both the non-linear vortex frequency and non-linear vo...
0912.5521v1
2010-10-01
Ferromagnetic resonance study of Co/Pd/Co/Ni multilayers with perpendicular anisotropy irradiated with Helium ions
We present a ferromagnetic resonance (FMR) study of the effect of Helium ion irradiation on the magnetic anisotropy, the linewidth and the Gilbert damping of a Co/Ni multilayer coupled to Co/Pd bilayers. The perpendicular magnetic anisotropy decreases linearly with He ion fluence, leading to a transition to in-plane ma...
1010.0268v2
2010-11-23
Ultra-fast magnetisation rates within the Landau-Lifshitz-Bloch model
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 $S \rightarrow \infty$ to the atomistic Landau-Lifshitz-Gilbert (LLG) Langevin dyna...
1011.5054v1
2011-10-15
Atomistic spin dynamic method with both damping and moment of inertia effects included from first principles
We consider spin dynamics for implementation in an atomistic framework and we address the feasibility of capturing processes in the femtosecond regime by inclusion of moment of inertia. In the spirit of an {\it s-d} -like interaction between the magnetization and electron spin, we derive a generalized equation of motio...
1110.3387v2
2011-10-24
CoB/Ni-Based Multilayer Nanowire with High-Speed Domain Wall Motion under Low Current Control
The spin-transfer torque motion of magnetic domain walls (DWs) in a CoB/Ni-based nanowire driven by a low current density of (1.12\pm0.8)\times10^{11} A m^{-2} has been observed indirectly by magnetotransport measurements. A high DW velocity of 85\pm4 m/s at zero field was measured at the threshold current density. Upo...
1110.5112v3
2012-09-17
Nonlinear emission of spin-wave caustics from an edge mode of a micro-structured Co2Mn0.6Fe0.4Si waveguide
Magnetic Heusler materials with very low Gilbert damping are expected to show novel magnonic transport phenomena. We report nonlinear generation of higher harmonics leading to the emission of caustic spin-wave beams in a low-damping, micro-structured Co2Mn0.6Fe0.4Si Heusler waveguide. The source for the higher harmonic...
1209.3669v2
2013-07-10
Scaling of spin Hall angle in 3d, 4d and 5d metals from Y3Fe5O12/metal spin pumping
Pure spin currents generated by spin pumping in ferromagnet/nonmagnet (FM/NM) bilayers produce inverse spin Hall effect (ISHE) voltages in the NM, from which spin pumping and transport characteristics of the NM can be extracted. Due to its exceptionally low damping, Y3Fe5O12 (YIG) is an important and widely used FM for...
1307.2648v2
2013-11-25
Spin-wave excitation and propagation in microstructured waveguides of yttrium iron garnet (YIG)/Pt bilayers
We present an experimental study of spin-wave excitation and propagation in microstructured waveguides patterned from a 100 nm thick yttrium iron garnet (YIG)/platinum (Pt) bilayer. The life time of the spin waves is found to be more than an order of magnitude higher than in comparably sized metallic structures despite...
1311.6305v1
2014-10-02
Investigation of the temperature-dependence of ferromagnetic resonance and spin waves in Co2FeAl0.5Si0.5
Co2FeAl0.5Si0.5 (CFAS) is a Heusler compound that is of interest for spintronics applications, due to its high spin polarization and relatively low Gilbert damping constant. In this study, the behavior of ferromagnetic resonance as a function of temperature was investigated in CFAS, yielding a decreasing trend of dampi...
1410.0439v1
2014-12-12
Spin waves in micro-structured yttrium iron garnet nanometer-thick films
We investigated the spin-wave propagation in a micro-structured yttrium iron garnet waveguide of $40$ nm thickness. Utilizing spatially-resolved Brillouin light scattering microscopy, an exponential decay of the spin-wave amplitude of $(10.06 \pm 0.83)$ $\mu$m was observed. This leads to an estimated Gilbert damping co...
1412.4032v1
2016-04-16
A broadband Ferromagnetic Resonance dipper probe for magnetic damping measurements from 4.2 K to 300 K
A dipper probe for broadband Ferromagnetic Resonance (FMR) operating from 4.2 K to room temperature is described. The apparatus is based on a 2-port transmitted microwave signal measurement with a grounded coplanar waveguide. The waveguide generates a microwave field and records the sample response. A 3-stage dipper de...
1604.04688v1
2016-05-27
A reduced model for precessional switching of thin-film nanomagnets under the influence of spin-torque
We study the magnetization dynamics of thin-film magnetic elements with in-plane magnetization subject to a spin-current flowing perpendicular to the film plane. We derive a reduced partial differential equation for the in-plane magnetization angle in a weakly damped regime. We then apply this model to study the experi...
1605.08698v1
2016-06-21
Torsion Effects and LLG Equation
Based on the non-relativistic regime of the Dirac equation coupled to a torsion pseudo-vector, we study the dynamics of magnetization and how it is affected by the presence of torsion. We consider that torsion interacting terms in Dirac equation appear in two ways one of these is thhrough the covariant derivative consi...
1606.06610v1
2016-07-05
Magnetic moment of inertia within the breathing model
An essential property of magnetic devices is the relaxation rate in magnetic switching which strongly depends on the energy dissipation and magnetic inertia of the magnetization dynamics. Both parameters are commonly taken as a phenomenological entities. However very recently, a large effort has been dedicated to obtai...
1607.01307v1
2016-10-14
Nambu mechanics for stochastic magnetization dynamics
The Landau-Lifshitz-Gilbert (LLG) equation describes the dynamics of a damped magnetization vector that can be understood as a generalization of Larmor spin precession. The LLG equation cannot be deduced from the Hamiltonian framework, by introducing a coupling to a usual bath, but requires the introduction of addition...
1610.04598v2
2017-01-31
Lack of correlation between the spin mixing conductance and the ISHE-generated voltages in CoFeB/Pt,Ta bilayers
We investigate spin pumping phenomena in polycrystalline CoFeB/Pt and CoFeB/Ta bilayers and the correlation between the effective spin mixing conductance $g^{\uparrow\downarrow}_{\rm eff}$ and the obtained voltages generated by the spin-to-charge current conversion via the inverse spin Hall effect in the Pt and Ta laye...
1701.09110v1
2017-06-05
Consistent microscopic analysis of spin pumping effects
We present a consistent microscopic study of spin pumping effects for both metallic and insulating ferromagnets. As for metallic case, we present a simple quantum mechanical picture of the effect as due to the electron spin flip as a result of a nonadiabatic (off-diagonal) spin gauge field. The effect of interface spin...
1706.01185v1
2018-03-04
Optimization of Time-Resolved Magneto-optical Kerr Effect Signals for Magnetization Dynamics Measurements
Recently magnetic storage and magnetic memory have shifted towards the use of magnetic thin films with perpendicular magnetic anisotropy (PMA). Understanding the magnetic damping in these materials is crucial, but normal Ferromagnetic Resonance (FMR) measurements face some limitations. The desire to quantify the dampin...
1803.01280v2
2018-05-04
Superparamagnetic Relaxation Driven by Colored Noise
A theoretical investigation of magnetic relaxation processes in single domain particles driven by colored noise is presented. Two approaches are considered; the Landau-Lifshitz-Miyazaki-Seki equation, which is a Langevin dynamics model based on the introduction of an Ornstein-Uhlenbeck correlated noise into the Landau-...
1805.01776v2
2018-06-02
Ultra-low damping insulating magnetic thin films get perpendicular
A magnetic material combining low losses and large Perpendicular Magnetic Anisotropy (PMA) is still a missing brick in the magnonic and spintronic fields. We report here on the growth of ultrathin Bismuth doped Y$_{3}$Fe$_{5}$O$_{12}$ (BiYIG) films on Gd$_{3}$Ga$_{5}$O$_{12}$ (GGG) and substituted GGG (sGGG) (111) orie...
1806.00658v1
2018-06-12
Dynamical and current-induced Dzyaloshinskii-Moriya interaction: Role for damping, gyromagnetism, and current-induced torques in noncollinear magnets
Both applied electric currents and magnetization dynamics modify the Dzyaloshinskii-Moriya interaction (DMI), which we call current-induced DMI (CIDMI) and dynamical DMI (DDMI), respectively. We report a theory of CIDMI and DDMI. The inverse of CIDMI consists in charge pumping by a time-dependent gradient of magnetizat...
1806.04782v3
2018-10-11
Propagating spin waves in nanometer-thick yttrium iron garnet films: Dependence on wave vector, magnetic field strength and angle
We present a comprehensive investigation of propagating spin waves in nanometer-thick yttrium iron garnet (YIG) films. We use broadband spin-wave spectroscopy with integrated coplanar waveguides (CPWs) and microstrip antennas on top of continuous and patterned YIG films to characterize spin waves with wave vectors up t...
1810.04973v1
2019-05-30
Predicting New Iron Garnet Thin Films with Perpendicular Magnetic Anisotropy
Perpendicular magnetic anisotropy (PMA) is a necessary condition for many spintronic applications like spin-orbit torques switching, logic and memory devices. An important class of magnetic insulators with low Gilbert damping at room temperature are iron garnets, which only have a few PMA types such as terbium and sama...
1905.13042v1
2019-07-17
Inhomogeneous domain walls in spintronic nanowires
In case of a spin-polarized current, the magnetization dynamics in nanowires are governed by the classical Landau-Lifschitz equation with Gilbert damping term, augmented by a typically non-variational Slonczewski term. Taking axial symmetry into account, we study the existence of domain wall type coherent structure sol...
1907.07470v2