Content of SPECIAL TOPIC — Advanced magnonics in our journal

Published in last 1 year |  In last 2 years |  In last 3 years |  All Please wait a minute... For selected: Download citations EndNote Ris BibTeX Toggle thumbnails Select Magnon-magnon coupling in noncollinear synthetic antiferromagnets Tengfei Zhang(张腾飞), Quwen Wang(王曲文), Min Chen(陈敏), Jie Dong(董洁), Qian Zhao(赵乾), Zimu Li(李子木), Qingfang Liu(刘青芳), Jianbo Wang(王建波), and Jinwu Wei(魏晋武) Chin. Phys. B, 2025, 34 (5): 057201.   DOI: 10.1088/1674-1056/adb26b Abstract （461）   HTML （4）    PDF （2123KB）（234）       Knowledge map    We report a theoretical analysis of magnon-magnon coupling in a noncollinear magnetic sandwiched structure with interlayer exchange interaction, which consists of two ferromagnetic layers with perpendicular and in-plane magnetic anisotropy, respectively. Based on the Landau-Lifshitz equation, the spin wave dispersion is derived, and then the frequency gap is observed due to the magnon-magnon coupling effect induced by symmetry breaking. The influence of saturation magnetization, exchange coupling interaction, perpendicular magnetic anisotropy, and wave vector on the coupling strength is studied in detail. We find that the coupling strength is strongly dependent on the saturation magnetization and a small saturation magnetization can lead to strong coupling strength. By selecting the appropriate magnetic materials, the ultra-strong coupling regime can be achieved. The precession information in time domain is solved and the alternating change of the precession components in two ferromagnetic layers implies the exchange of energy and information. Select Nonreciprocal microwave-optical entanglement in Kerr-modified cavity optomagnomechanics Ming-Yue Liu(刘明月), Yuan Gong(龚媛), Jiaojiao Chen(陈姣姣), Yan-Wei Wang(王艳伟), and Wei Xiong(熊伟) Chin. Phys. B, 2025, 34 (5): 057202.   DOI: 10.1088/1674-1056/adb735 Abstract （273）   HTML （0）    PDF （1863KB）（223）       Knowledge map    Microwave-optical entanglement is essential for efficient quantum communication, secure information transfer, and integrating microwave and optical quantum systems to advance hybrid quantum technologies. In this work, we demonstrate how the magnon Kerr effect can be harnessed to generate and control nonreciprocal entanglement in cavity optomagnomechanics (COMM). This effect induces magnon frequency shifts and introduces pair-magnon interactions, both of which are tunable through the magnetic field direction, enabling nonreciprocal behavior. By adjusting system parameters such as magnon frequency detuning, we show that magnon-phonon, microwave-optical photon-photon, and optical photon-magnon entanglement can be nonreciprocally enhanced and rendered more robust against thermal noise. Additionally, the nonreciprocity of entanglement can be selectively controlled, and ideal nonreciprocal entanglement is achievable. This work paves the way for designing nonreciprocal quantum devices across the microwave and optical regimes, leveraging the unique properties of the magnon Kerr effect in COMM. Select Bifurcation of the bound states in the continuum in a dissipative cavity magnonic system Xinlin Mi(米锌林), Lijun Yan(闫丽君), Bimu Yao(姚碧霂), Shishen Yan(颜世申), Jinwei Rao(饶金威), and Lihui Bai(柏利慧) Chin. Phys. B, 2025, 34 (6): 067508.   DOI: 10.1088/1674-1056/add4e4 Abstract （196）   HTML （0）    PDF （1373KB）（120）       Knowledge map    We report the bifurcation of bound states in the continuum (BICs) in a dissipative cavity magnonic system, where a BIC splits into a pair of BICs. We theoretically analyze BICs in a dissipative cavity magnonic system and derive the critical condition for BICs bifurcation. Based on the theoretical results, we experimentally tune the dissipative photon-magnon coupling strength and demonstrate precise control over the detuning and number of BICs. When the dissipative coupling strength reaches a critical value, we observe the bifurcation of BICs, which is consistent with the theoretical prediction. Our systematic investigation of the evolution of BICs concerning the dissipative coupling strength and the discovery of the BIC bifurcation may enhance the sensitivity of BICs to external perturbations, potentially enabling applications in ultrasensitive detection. Select First- and second-order magnonic topologies in the ferromagnetic breathing SSH model modulated by non-Hermitian effects Huasu Fu(付华宿), Lichuan Zhang(张礼川), Rami Mrad, Yuee Xie(谢月娥), and Yuanping Chen(陈元平) Chin. Phys. B, 2025, 34 (6): 067506.   DOI: 10.1088/1674-1056/addaa0 Abstract （185）   HTML （0）    PDF （2171KB）（87）       Knowledge map    We investigate magnonic topology in the breathing Su-Schrieffer-Heeger (SSH) model, incorporating non-Hermitian effects. Our results demonstrate the coexistence of first- and second-order magnonic topologies, with non-Hermitian effects exhibiting size-dependent behavior. In two-dimensional systems, non-Hermitian terms induce a flat band and gap closure along high-symmetry paths, whereas in one-dimensional systems, a finite band gap persists for small system sizes. Additionally, the corner states remain robust, and a pronounced non-Hermitian skin effect emerges. Our findings provide new insights into magnon-based devices, emphasizing the impact of non-Hermitian effects on their design and functionality. Select Control of the magnonic excitation under the joint mechanism of magnetostrictive effect and magnetocrystalline anisotropy Saisai Yu(鱼赛赛), Junbo Liu(刘竣菠), and Hao Xiong(熊豪) Chin. Phys. B, 2025, 34 (6): 068502.   DOI: 10.1088/1674-1056/add67c Abstract （178）   HTML （0）    PDF （2984KB）（193）       Knowledge map    Magnetostrictive effects and magnetocrystalline anisotropy are fundamental physical properties governing magnon dynamics in magnetic systems. Recent evidence shows that strain-mediated magnetostrictive coupling provides an effective pathway for modulating magnonic excitation through quantum interference. Nevertheless, the microscopic origins of magnetocrystalline anisotropy in manipulating magnon excitation pathways, particularly regarding magnonic Kerr nonlinearity and crystal direction constraints, require further investigation. In this study, we construct a dual-frequency driven magnomechanical model based on yttrium iron garnet (YIG) spheres. By introducing a Hamiltonian with the magnonic Kerr nonlinear term, we combine the Heisenberg-Langevin equations and the mean field approximation to analytically solve for the driving efficiency $\eta$, and we base our analysis on experimental parameters to evaluate the impacts of the magnonic Kerr coefficient ($K$), driving field ($B_1$) and YIG size. The results show that the magnetocrystalline anisotropy induces a MHz-scale frequency shift, splitting the transmission spectrum from a Lorentzian line shape into asymmetric Fano resonance double peaks. The orientation of the external magnetic field (aligned with the [100] or [110] crystallographic axis) allows precise control over the sign of the magnonic Kerr coefficient $K$, thereby enabling a reversal in the direction of the frequency shift. A strong driving field $B_1$ not only enables controllable switching of the state but also adjusts the switching bandwidth. Furthermore, we show the transition of the dynamical response mechanism of the excitation efficiency spectrum with varying YIG sphere sizes. The study shows the dynamic control mechanism of the magnetocrystalline anisotropy on magnon switching and provides a theoretical foundation for size optimization and nonlinear energy manipulation in spintronic device design. Select Magnon behavior in YIG film under microwave excitation investigated by Brillouin light scattering Guofu Xu(徐国服), Kang An(安康), Wenjun Ma(马文俊), Xiling Li(李喜玲), C. K. Ong, Chi Zhang(张驰), and Guozhi Chai(柴国志) Chin. Phys. B, 2025, 34 (6): 067507.   DOI: 10.1088/1674-1056/add24c Abstract （164）   HTML （0）    PDF （825KB）（135）       Knowledge map    We utilize conventional wave-vector-resolved Brillouin light scattering technology to investigate the spin wave response in YIG thin films under high-power microwave excitation. By varying the microwave frequency, external bias magnetic field, and in-plane wave vector, in addition to observing the dipole-exchange spin waves excited by parallel parametric pumping, we further observe broadband spin wave excitation within the dipole-exchange spin wave spectrum. This broadband excitation results from the combined effects of parallel and perpendicular parametric pumping, induced by irregularities in the excitation geometry, as well as magnon-magnon scattering arising from the absence of certain spin wave modes. Our findings offer new insights into the mechanisms of energy dissipation and relaxation processes caused by spin wave excitation in magnetic devices operating at high power. Select A two-stage injection locking amplifier based on a cavity magnonic oscillator Mun Kim, Chunlei Zhang, Chenyang Lu, Jacob Burgess, and Can-Ming Hu Chin. Phys. B, 2025, 34 (6): 067104.   DOI: 10.1088/1674-1056/add1bf Abstract （161）   HTML （1）    PDF （3114KB）（57）       Knowledge map    A cavity magnonic oscillator uses the coupling of a planar transmission line oscillator (cavity) and spin excitations (magnons) in a ferrimagnetic material to achieve superior frequency stability and reduced phase noise. Like many low phase noise oscillators, a cavity magnonic oscillator faces the challenge that its narrow resonance profile is not well suited for injection locking amplification. This work presents an improved design for such an oscillator configured as an injection locking amplifier (ILA) with an extended lock range. The proposed design features a two-stage architecture, consisting of a pre-amplification oscillator and a cavity magnonic oscillator, separated by an isolator to prevent backward locking. By optimizing the circuit parameters of each stage, the proposed design achieved an order of magnitude increase in lock range, when compared to its predecessors, all while preserving the phase noise quality of the input, making it well-suited for narrowband, sensitive signal amplification. Furthermore, this work provides a method for using oscillators with high spectral purity as injection locking amplifiers.