Open AccessEmergent magnonic singularities in anti parity-time symmetric synthetic antiferromagnets
Author(s) -
Chaowei Sui,
Shaohua Yuan,
Xi-guang Wang,
J. Berakdar,
Chenglong Jia
Publication year - 2022
Publication title -
new journal of physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.584
H-Index - 190
ISSN - 1367-2630
DOI - 10.1088/1367-2630/ac52c1
Subject(s) - physics , antiferromagnetism , gravitational singularity , parity (physics) , condensed matter physics , quantum mechanics
We study the impact of the transition across the anti-parity-time (anti- PT ) symmetry breaking point on the low-energy spin excitations in a synthetic antiferromagnet (SyAFM) that consists of two magnetic layers coupled antiferromagnetically via the Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction. When varying the interlayer (RKKY) coupling strength a degeneracy point (exceptional point) is reached beyond which the system enters the anti- PT symmetry-broken phase. This phase is marked by the emergence of a finite net magnetization and low-lying excitations beyond the Goldstone modes in the anti- PT symmetry-preserved phase. For systems hosting an interfacial Dzyaloshinskii–Moriya interaction, we find a bound state in the continuum with a maximal coherent superposition of SyAFM excitations without any radiation. Analytical results for linearized models are corroborated with full numerical micromagnetic simulations endorsing the robustness and generalities of the theory predictions.