Title: Exceptional points in classical spin dynamics

Abstract

Abstract 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 ( $$$${\mathscr{P}}{\mathscr{T}}$$$$ $PT$ )-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.

Authors:

Galda, Alexey; Vinokur, Valerii M.

• Search DOE PAGES for author "Vinokur, Valerii M."
• Search DOE PAGES for ORCID "0000-0002-0977-3515"

Publication Date:

Mon Nov 25 00:00:00 EST 2019

Research Org.:

Argonne National Laboratory (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division

OSTI Identifier:

1619592

Alternate Identifier(s):

OSTI ID: 1578048

Grant/Contract Number:  

AC02-06CH11357

Resource Type:

Published Article

Journal Name:

Scientific Reports

Additional Journal Information:

Journal Name: Scientific Reports Journal Volume: 9 Journal Issue: 1; Journal ID: ISSN 2045-2322

Publisher:

Nature Publishing Group

Country of Publication:

United Kingdom

Language:

English

Subject:

36 MATERIALS SCIENCE