Strong to ultra-strong coherent coupling measurements in a YIG/cavity system at room temperature

We present an experimental study of the strong to ultra-strong coupling regimes at room temperature in frequency-reconfigurable 3D re-entrant cavities coupled with a YIG slab. The observed coupling rate, defined as the ratio of the coupling strength to the cavity frequency of interest, ranges from 12% to 59%. We show that certain considerations must be taken into account when analyzing the polaritonic branches of a cavity spintronic device where the RF field is highly focused in the magnetic material. Our observations are in excellent agreement with electromagnetic finite element simulations in the frequency domain.Comment: 19 pages, 12 figure

Near-Field diffraction of spin waves

International audienc

Manifestation of the coupling phase in microwave cavity magnonics

The interaction between microwave photons and magnons is well understood and originates from the Zeeman coupling between spins and a magnetic field. Interestingly, the magnon/photon interaction is accompanied by a phase factor which can usually be neglected. However, under the rotating wave approximation, if two magnon modes simultaneously couple with two cavity resonances, this phase cannot be ignored as it changes the physics of the system. We consider two such systems, each differing by the sign of one of the magnon/photon coupling strengths. This simple difference, originating from the various coupling phases in the system, is shown to preserve, or destroy, two potential applications of hybrid photon/magnon systems, namely dark mode memories and cavity-mediated coupling. The observable consequences of the coupling phase in this system is akin to the manifestation of a discrete Pancharatnam-Berry phase, which may be useful for quantum information processing

Probing Spin Wave Diffraction Patterns of Curved Antennas

We report on the dependence of curvilinear shaped coplanar waveguides on the near-field diffraction patterns of spin waves propagating in perpendicularly magnetized thin films. Implementing the propagating spin waves spectroscopy techniques on either concentrically or eccentrically shaped antennas, we show how the link budget is directly affected by the spin wave interference, in good agreement with near-field diffraction simulations. This work demonstrates the feasibility to inductively probe a magnon interference pattern with a resolution down to 1$\mu$m$^2$, and provides a methodology for shaping spin wave beams from an antenna design. This methodology is successfully implemented in the case study of a spin wave Young's interference experiment

Current-induced spin-wave Doppler shift

Nous présentons dans cette thèse une manière originale d'étudier le couplage par transfert de spin entre l'aimantation d'un métal ferromagnétique et un courant d'électrons polarisés en mesurant un décalage Doppler d'onde de spin induit par un courant élecIn this thesis, we propose a new way of studying the spin transfer, i.e. the coupling between a current of spin-polarized electrons and the magnetization of a ferromagnetic metal, by measuring a current-induced Doppler eect for the spin waves. A transfe

Current-induced spin-wave Doppler shift

Nous présentons dans cette thèse une manière originale d'étudier le couplage par transfert de spin entre l'aimantation d'un métal ferromagnétique et un courant d'électrons polarisés en mesurant un décalage Doppler d'onde de spin induit par un courant électrique. Le passage d'un courant à travers une configuration non-uniforme de l'aimantation, telle qu'une onde de spin, est susceptible d'entraîner un transfert de spin entre le courant et l'aimantation locale. Dans le cadre de l'approximation adiabatique, où le courant de spin est en tout point colinéaire à l'aimantation locale, il en résulte simplement un décalage en fréquence des modes propres d'onde de spin. Ce décalage est proportionnel au produit vecteur d'onde - courant de spin, ce qui suggère l'analogie avec un décalage Doppler usuel. La mesure de ce décalage Doppler d'onde de spin induit donne directement le degré de polarisation en spin du courant électrique dans le volume du matériau.In this thesis, we propose a new way of studying the spin transfer, i.e. the coupling between a current of spin-polarized electrons and the magnetization of a ferromagnetic metal, by measuring a current-induced Doppler eect for the spin waves. A transfer of spin angular momentum is indeed expected when electrons ow through an inhomogeneous configuration of the magnetization, such as one provided by a spin wave. In the adiabatic approximation, for which the spin of the owing electrons aligns instantaneously with the magnetization, the spin wave modes are simply shifted in frquency. This frquency shift is proportional to the wave vector and the current density, which suggests an analogy with regular Doppler eects. The spin polarization of the electrical current in the ferromagnetic metal can be deduced directly from the measured current-induced spin-wave Doppler shift

Décalage Doppler d'ondes de spin induit par un courant électrique

Nous présentons dans cette thèse une manière originale d'étudier le couplage par transfert de spin entre l'aimantation d'un métal ferromagnétique et un courant d'électrons polarisés en mesurant un décalage Doppler d'onde de spin induit par un courant électrique. Le passage d'un courant à travers une configuration non-uniforme de l'aimantation, telle qu'une onde de spin, est susceptible d'entraîner un transfert de spin entre le courant et l'aimantation locale. Dans le cadre de l'approximation adiabatique, où le courant de spin est en tout point colinéaire à l'aimantation locale, il en résulte simplement un décalage en fréquence des modes propres d'onde de spin. Ce décalage est proportionnel au produit vecteur d'onde - courant de spin, ce qui suggère l'analogie avec un décalage Doppler usuel. La mesure de ce décalage Doppler d'onde de spin induit donne directement le degré de polarisation en spin du courant électrique dans le volume du matériau.In this thesis, we propose a new way of studying the spin transfer, i.e. the coupling between a current of spin-polarized electrons and the magnetization of a ferromagnetic metal, by measuring a current-induced Doppler eect for the spin waves. A transfer of spin angular momentum is indeed expected when electrons ow through an inhomogeneous configuration of the magnetization, such as one provided by a spin wave. In the adiabatic approximation, for which the spin of the owing electrons aligns instantaneously with the magnetization, the spin wave modes are simply shifted in frequency. This frequency shift is proportional to the wave vector and the current density, which suggests an analogy with regular Doppler eects. The spin polarization of the electrical current in the ferromagnetic metal can be deduced directly from the measured current-induced spin-wave Doppler shift.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF