Exceptional points in classical spin dynamics

Non-conservative physical systems admit a special kind of spectral degeneracy, known as exceptional point (EP), at which eigenvalues and eigenvectors of the corresponding non-Hermitian Hamiltonian coalesce. Dynamical parametric encircling of the EP can lead to non-adiabatic evolution associated with...

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Bibliographic Details
Published in:Scientific reports 2019-11, Vol.9 (1), p.17484-7, Article 17484
Main Authors: Galda, Alexey, Vinokur, Valerii M.
Format: Article
Language:English
Subjects:
639/301/119/2793
639/766/119/1001
Adiabatic
Asymmetry
Efficiency
Eigenvalues
Humanities and Social Sciences
Magnetic fields
MATERIALS SCIENCE
multidisciplinary
Optics
Phase transitions
Protocol
Science
Science (multidisciplinary)
Symmetry
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Summary:Non-conservative physical systems admit a special kind of spectral degeneracy, known as exceptional point (EP), at which eigenvalues and eigenvectors of the corresponding non-Hermitian Hamiltonian coalesce. Dynamical parametric encircling of the EP can lead to non-adiabatic evolution associated with a state flip, a sharp transition between the resonant modes. Physical consequences of the dynamical encircling of EPs in open dissipative systems have been explored in optics and photonics. Building on the recent progress in understanding the parity-time ( P T )-symmetric dynamics in spin systems, we use topological properties of EPs to implement chiral non-reciprocal transmission of a spin through the material with non-uniform magnetization, like helical magnet. We consider an exemplary system, spin-torque-driven single spin described by the time-dependent non-Hermitian Hamiltonian. We show that encircling individual EPs in a parameter space results in non-reciprocal spin dynamics and find the range of optimal protocol parameters for high-efficiency asymmetric spin filter based on this effect. Our findings offer a platform for non-reciprocal spin devices for spintronics and magnonics.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-019-53455-0