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We report an experimental observation of magnon-magnon coupling in interlayer exchange coupled synthetic antiferromagnets of FeCoB/Ru/FeCoB layers. An anticrossing gap of spin-wave resonance between acoustic and optic modes appears when the external magnetic field points to the direction tilted from the spin-wave propagation. The magnitude of the gap (i.e., coupling strength) can be controlled by changing the direction of the in-plane magnetic field and also enhanced by increasing the wave number of excited spin waves. We find that the coupling strength under the specified conditions is larger than the dissipation rates of both the resonance modes, indicating that a strong coupling regime is satisfied. A theoretical analysis based on the Landau-Lifshitz equation shows quantitative agreement with the experiments and indicates that the anticrossing gap appears when the exchange symmetry of two magnetizations is broken by the spin-wave excitation.
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http://dx.doi.org/10.1103/PhysRevLett.125.017203 | DOI Listing |
Phys Rev Lett
June 2025
SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, 2575 Sand Hill Road, Menlo Park, California 94025, USA.
In light of recent experimental data indicating a substantial thermal Hall effect in square lattice antiferromagnetic Mott insulators, we investigate whether a simple Mott insulator can sustain a finite thermal Hall effect. We verify that the answer is "no" if one performs calculations within a spin-only low-energy effective spin model with noninteracting magnons. However, by performing determinant quantum Monte Carlo simulations, we show the single-band t-t^{'}-U Hubbard model coupled to an orbital magnetic field does support a finite thermal Hall effect when t^{'}≠0 and B≠0 in the Mott insulating phase.
View Article and Find Full Text PDFPhys Rev Lett
June 2025
Tohoku University, WPI Advanced Institute for Materials Research, 2-1-1 Katahira, Sendai 980-8577, Japan.
We investigate the nonlinear coupling between acoustic (ac) and optical (op) modes in the coupled magnetization dynamics of synthetic antiferromagnets, utilizing current-driven resonance spectroscopy. A clear spectral splitting is evident in the ac mode when strongly excited by the radio frequency current at a driving frequency half that of the op mode resonance. The Landau-Lifshitz phenomenology aligns with the experimental observations, affirming the coupling of the radio-frequency-excited ac and op modes through three-magnon mixing.
View Article and Find Full Text PDFJ Am Chem Soc
June 2025
Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Fuzhou, Fujian 350207, China.
Copper(II) hybrid organic-inorganic perovskites (HOIPs) offer a unique platform to explore magnetic interactions responsible for ferro- or antiferromagnetic order; yet, their potential for coherent magnon dynamics, a cornerstone of spintronic technologies, remains underdeveloped. Unlike conventional ferromagnets, the structural parameters influencing magnon generation, propagation, and control in HOIPs are poorly understood. Here, we engineer interlayer and intralayer exchange interactions in A-type Dion-Jacobson (DJ) phase Cu(II)-based HOIPs to achieve robust magnon-magnon coupling.
View Article and Find Full Text PDFNano Lett
June 2025
Department of Materials, ETH Zurich, Zurich 8093, Switzerland.
Harnessing spin currents to control magnon dynamics enables new functionalities in magnonic devices. Here, we demonstrate current-controlled magnon-magnon coupling between cavity and boundary modes in an ultrathin film of Bi-doped yttrium iron garnet (BiYIG). Cavity modes emerge in a BiYIG region between two Pt nanostripes, where interfacial anisotropy modifies the magnon dispersion.
View Article and Find Full Text PDFSci Adv
May 2025
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Parametric amplification, where one signal is enhanced by the action of another, offers both practical utility for boosting weak signals and fundamental insights into the nonlinear coupling between degrees of freedom. In condensed matter systems, interactions between collective modes offer avenues for nonlinear coherent manipulation of coupled excitations and quantum phases. Antiferromagnets, with inherently coupled magnon modes, provide a promising platform for nonlinear control of spin waves and magnetization.
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