Exceptional points in classical spin dynamics

Galda, Alexey; Vinokur, V. M.

doi:10.1038/s41598-019-53455-0

Cited by 19 publications

(16 citation statements)

References 32 publications

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“…In (26), h is defined by the equation (19). As in the previous subsection, we expand the magnetisation vector over an orthonormal basis {A, B, M (0) }:…”

Section: B Perturbation Of Latitudinal Fixed Pointsmentioning

confidence: 99%

Stable solitons in a nearly PT-symmetric ferromagnet with spin-transfer torque

Barashenkov

Chernyavsky

2020

Physica D: Nonlinear Phenomena

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We consider the Landau-Lifshitz equation for the spin torque oscillator -a uniaxial ferromagnet in an external magnetic field with polarised spin current driven through it. In the absence of the Gilbert damping, the equation turns out to be PT -symmetric. We interpret the PT -symmetry as a balance between gain and loss -and identify the gaining and losing modes. In the vicinity of the bifurcation point of a uniform static state of magnetisation, the PT -symmetric Landau-Lifshitz equation with a small dissipative perturbation reduces to a nonlinear Schrödinger equation with a quadratic nonlinearity. The analysis of the Schrödinger dynamics demonstrates that the spin torque oscillator supports stable magnetic solitons. The PT near-symmetry is crucial for the soliton stability: the addition of a finite dissipative term to the Landau-Lifshitz equation destabilises all solitons that we have found.

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“…In (26), h is defined by the equation (19). As in the previous subsection, we expand the magnetisation vector over an orthonormal basis {A, B, M (0) }:…”

Section: B Perturbation Of Latitudinal Fixed Pointsmentioning

confidence: 99%

Stable solitons in a nearly PT-symmetric ferromagnet with spin-transfer torque

Barashenkov

Chernyavsky

2020

Physica D: Nonlinear Phenomena

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“…While initially EPs were regarded as a mathematical-physics concept, in the last decade there has been a growing interest on EPs from the experimental point of view in such areas as atomic spectra measurements [8] , microwave cavity experiments [9][10][11][12][13] , chaotic optical microcavities [14] or optomechanical systems [15] . Interestingly, exceptional points arise also in classical systems, such as coupled electric oscillators [16,17] , optical systems [18] , classical spin dynamics [19,20] , and general dissipative classical systems [21] .…”

mentioning

confidence: 99%

“…Very recently, there has been growing attention on EPs in the area of magnetism with theoretical works on spin dynamics [19,20,29] and spin-orbit systems [30] . Experimental results have been achieved in passive magnonic structures [31] or opto-magnonic systems [32] .…”

mentioning

confidence: 99%

Exceptional points controlling oscillation death in coupled spintronic nano-oscillators

Wittrock¹,

Perna²,

Lebrun³

et al. 2022

Preprint

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The emergence of exceptional points (EPs) in the parameter space of a (2D) eigenvalue problem is studied in a general sense in mathematical physics. In coupled systems, it gives rise to unique physical phenomena upon which novel approaches for the development of seminal types of highly sensitive sensors shall leverage their fascinating properties. Here, we demonstrate at room temperature the emergence of EPs in coupled spintronic nanoscale oscillators, coming along with the observation of amplitude death of self-oscillations and other complex dynamics. The main experimental features are properly described by the linearized theory of coupled system dynamics we develop. Interestingly, these spintronic nanoscale oscillators are deployment-ready in different applicational technologies, such as field, current or rotation sensors, radiofrequeny and wireless devices and, more recently, novel neuromorphic hardware solutions. Their unique and versatile properties, notably their large nonlinear behavior open up unprecedented perspectives in experiments as well as in theory on the physics of exceptional points. Furthermore, the exploitation of EPs in spintronics devises a new paradigm for ultrasensitive nanoscale sensors and the implementation of complex dynamics in the framework of non-conventional computing.

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“…Magnons, i.e., the collective excitations of magnetic systems, are bosonic quasiparticles whose number is not conserved and whose dynamics is intrinsically non-Hermitian [25][26][27][28][29][30]. Their fundamental properties, including their lifetime, can be easily tuned via external fields and drives, making them promising solid-state candidates for the exploration of non-Hermitian topological phenomena [31][32][33][34].…”

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confidence: 99%

Non-Hermitian skin effect in magnetic systems

Deng,

Flebus

2021

Preprint

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Far from being limited to a trivial generalization of their Hermitian counterparts, non-Hermitian topological phases have gained widespread interest due to their unique properties. One of the most striking non-Hermitian phenomena is the skin effect, i.e., the localization of a macroscopic fraction of bulk eigenstates at a boundary, which underlies the breakdown of the bulk-edge correspondence.Here we investigate the emergence of the skin effect in magnetic insulating systems by developing a phenomenological approach to describing magnetic dissipation within a lattice model. Focusing on a spin-orbit-coupled van der Waals (vdW) ferromagnet with spin-nonconserving magnon-phonon interactions, we find that the magnetic skin effect emerges in an appropriate temperature regime. Our results suggest that the interference between Dzyaloshinskii-Moriya interaction (DMI) and nonlocal magnetic dissipation plays a key role in the accumulation of bulk states at the boundaries.

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Exceptional points in classical spin dynamics

Cited by 19 publications

References 32 publications

Stable solitons in a nearly PT-symmetric ferromagnet with spin-transfer torque

Stable solitons in a nearly PT-symmetric ferromagnet with spin-transfer torque

Exceptional points controlling oscillation death in coupled spintronic nano-oscillators

Non-Hermitian skin effect in magnetic systems

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