1,359,414 research outputs found
Magnon squeezing by two-tone driving of a qubit in cavity-magnon-qubit systems
No full textWe propose a scheme for preparing magnon squeezed states in a hybrid cavity-magnon-qubit system. The system consists of a microwave cavity that simultaneously couples to a magnon mode of a macroscopic yttrium-iron-garnet (YIG) sphere via the magnetic-dipole interaction and to a transmon-type superconducting qubit via the electric-dipole interaction. By far detuning from the magnon-qubit system, the microwave cavity is adiabatically eliminated. The magnon mode and the qubit then get effectively coupled via the mediation of virtual photons of the microwave cavity. We show that by driving the qubit with two microwave fields and by appropriately choosing the drive frequencies and strengths, magnonic parametric amplification can be realized, which leads to magnon quadrature squeezing with the noise below vacuum fluctuation. We provide optimal conditions for achieving magnon squeezing, and moderate squeezing can be obtained using currently available parameters. The generated squeezed states are of a magnon mode involving more than spins and thus macroscopic quantum states. The work may find promising applications in quantum information processing and high-precision measurements based on magnons and in the study of macroscopic quantum states
Two-magnon Raman scattering in quadratic double-layer antiferromagnets
No full textTwo-magnon Raman spectra of ordered K3Mn2F7 are interpreted in terms of a two-dimensional four-sublattice spin-wave theory. In solving the equation of motion of the Green functions it is essential to include terms of the spin-wave Hamiltonian coupling the two magnon branches
Magnon-induced high-order sideband generation
No full textMagnon Kerr nonlinearity plays crucial roles in the study of cavity optomagnonics system and may bring many novel physical phenomena and important applications. In this work, we report the investigation of high- order sideband generation induced by magnon Kerr nonlinearity in a cavity-magnon system, which is critically lacking in this emerging research field. We uncover that the driving field plays a significant role in controlling the generation and amplification of the higher-order sidebands and the sideband spacing can be adjusted by regulating the beat frequency between the pump laser and the probe laser, which is extremely eventful for the spacing modulation of the sideband spectrum. Based on the recent experimental progress, our results deepen our cognition into optomagnonics nonlinearity and may find interesting applications in optical frequency metrology and optical communications
Temperature-dependent magnon torque in SrIrO3/NiO/ferromagnetic multilayers
No full textMagnetization switching driven by magnons is a promising technology capable of substantially decreasing energy dissipation and potential damage to spintronic devices. In this study, we investigated the temperature-dependent magnon torque effect in SrIrO3/NiO/ferromagnetic multilayers. It is found that the magnon-mediated damping-like spin–orbit torque (SOT) efficiency decreases with increasing temperature. Enhanced magnon transmission was observed in the vicinity of the blocking temperature of the NiO layer, which can be ascribed to the amplification of damping-like SOT efficiency by the spin fluctuations. More importantly, we have demonstrated that the magnon-mediated SOT is an effective method to manipulate a perpendicular magnetization, particularly using a critical switching current density that is pretty low, as evidenced by ∼ 4 × 105 A/cm2 for SrRuO3/NiO/SrIrO3 trilayers in this study. These findings suggest a promising avenue for the development of highly efficient spintronic devices operable through magnon currents
Magnon-exciton proximity coupling at a van der Waals heterointerface
No full textSpin and photonic systems are at the heart of modern information devices and emerging quantum technologies. An interplay between electron-hole pairs (excitons) in semiconductors and collective spin excitations (magnons) in magnetic crystals would bridge these heterogeneous systems, leveraging their individual assets in novel interconnected devices. Here, we report the magnon-exciton coupling at the interface between a magnetic thin film and an atomically-thin semiconductor. Our approach allies the long-lived magnons hosted in a film of yttrium iron garnet (YIG) to strongly-bound excitons in a flake of a transition metal dichalcogenide, MoSe. The magnons induce on the excitons a dynamical valley Zeeman effect ruled by interfacial exchange interactions. This nascent class of hybrid system suggests new opportunities for information transduction between microwave and optical regions
Coherent control of magnon radiative damping with local photon states
No full textA magnon, the collective excitation of ordered spins, can spontaneously radiate a travelling photon to an open system when decaying to the ground state. However, in contrast to electric dipoles, magnetic dipoles by magnons are more isolated from the environment, limiting their radiation and coherent communication with photons. The recent progresses in strongly coupled magnon-photon system have stimulated the manipulation of magnon radiation via tailoring the photon states. Here, by loading an yttrium iron garnet sphere in a one-dimensional waveguide cavity supporting both the travelling and standing photon modes, we demonstrate a significant magnon radiative damping that is proportional to the local density of photon states (LDOS). By modulating the magnitude and/or polarization of LDOS, we can flexibly tune the photon emission and magnon radiative damping. Our findings provide a way to manipulate photon emission from magnon radiation, which could help harness angular momentum generation, transfer, and storage in magnonics.QN/Bauer Grou
Magnon-phonon interactions in magnon spintronics
No full textNowadays, the interaction between phonon and magnon subsystems of a magnetic
medium is a hot topic of research. The complexity of phonon and magnon spectra,
the existence of both bulk and surface modes, the quantization effects, and the
dependence of magnon properties on applied magnetic field, make this field very
complex and intriguing. Moreover, the recent advances in the fields of
spin-caloritronics and magnon spintronics as well as the observation of the
spin Seebeck effect (SSE) in magnetic insulators points on the crucial role of
magnons in spin-caloric transport processes. In this review, we collect the
variety of different studies in which magnon-phonon interaction play important
role. The scope of the paper covers the wide range of phenomena starting from
the interaction of the coherent magnons with surface acoustic wave and
finishing with the formation of magnon supercurrents in the thermal gradients
Magnon-assisted tunnelling in van der Waals heterostructures based on CrBr3
No full textVan der Waals heterostructures, which are composed of layered two-dimensional materials, offer a platform to investigate a diverse range of physical phenomena and could be of use in a variety of applications. Heterostructures containing two-dimensional ferromagnets, such as chromium triiodide (CrI3), have recently been reported, which could allow two-dimensional spintronic devices to be developed. Here we study tunnelling through thin ferromagnetic chromium tribromide (CrBr3) barriers that are sandwiched between graphene electrodes. In devices with non-magnetic barriers, conservation of momentum can be relaxed by phonon-assisted tunnelling or by tunnelling through localized states. In contrast, in the devices with ferromagnetic barriers, the major tunnelling mechanisms are the emission of magnons at low temperatures and the scattering of electrons on localized magnetic excitations at temperatures above the Curie temperature. Magnetoresistance in the graphene electrodes further suggests induced spin–orbit coupling and proximity exchange via the ferromagnetic barrier. Tunnelling with magnon emission offers the possibility of spin injectio
Magnon-phonon interactions in magnetic insulators
No full textWe address the theory of magnon-phonon interactions and compute the corresponding quasiparticle and transport lifetimes in magnetic insulators, with a focus on yttrium iron garnet at intermediate temperatures from anisotropy- and exchange-mediated magnon-phonon interactions, the latter being derived from the volume dependence of the Curie temperature. We find in general weak effects of phonon scattering on magnon transport and the Gilbert damping of the macrospin Kittel mode. The magnon transport lifetime differs from the quasiparticle lifetime at shorter wavelengths.QN/Bauer Grou
Magnon antibunching in a nanomagnet
No full textWe investigate the correlations of magnons inside a nanomagnet and identify a regime of parameters where the magnons become antibunched, i.e., where there is a large probability for occupation of the single-magnon state. This antibunched state is very different from magnons at thermal equilibrium and microwave-driven coherent magnons. We further obtain the steady state analytically and describe the magnon dynamics numerically, and ascertain the stability of such antibunched magnons over a large window of magnetic anisotropy, damping and temperature. This means that the antibunched magnon state is feasible in a wide class of low-damping magnetic nanoparticles. To detect this quantum effect, we propose to transfer the quantum information of magnons to photons by magnon-photon coupling and then measure the correlations of photons to retrieve the magnon correlations. Our findings may provide a promising platform to study quantum-classical transitions and for designing a single magnon source
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