Nikita Kostylev

Ultrahigh cooperativity interactions between magnons and resonant photons in a YIG sphere

Resonant photon modes of a 5-mm-diameter yttrium iron garnet (YIG) sphere loaded in a cylindrical cavity in the 10\char21{}30-GHz frequency range are characterized as a function of applied dc magnetic field at millikelvin temperatures. The photon modes are confined mainly to the sphere and exhibited large mode filling factors in comparison to previous experiments, allowing ultrastrong coupling with the magnon spin-wave resonances. The largest observed coupling between photons and magnons is

Magnetization pinning in conducting films demonstrated using broadband ferromagnetic resonance

2g/2\ensuremath{\pi}=7.11

Plasmon-assisted high reflectivity and strong magneto-optical Kerr effect in permalloy gratings

GHz for a 15.5-GHz mode, corresponding to a cooperativity of

Superstrong coupling of a microwave cavity to yttrium iron garnet magnons

C=1.51\ifmmode\pm\else\textpm\fi{}0.47\ifmmode\times\else\texttimes\fi{}{10}^{7}

A 3D printed superconducting aluminium microwave cavity

. Complex modifications, beyond a simple multioscillator model, of the photon mode frequencies were observed between 0 and 0.1 T. Between 0.4 and 1 T, degenerate resonant photon modes were observed to interact with magnon spin-wave resonances with different coupling strengths, indicating time-reversal symmetry breaking due to the gyrotropic permeability of YIG. Bare dielectric resonator mode frequencies were determined by detuning magnon modes to significantly higher frequencies with strong magnetic fields. By comparing measured mode frequencies at 7 T with finite element modeling, a bare dielectric permittivity of

Determination of low loss in isotopically pure single crystal 28Si at low temperatures and single microwave photon energy

15.96\ifmmode\pm\else\textpm\fi{}0.02

Single-photon level study of microwave properties of lithium niobate at millikelvin temperatures

of the YIG crystal has been determined at about 20 mK.

Electromagnetic properties of terbium gallium garnet at millikelvin temperatures and low photon energy

The broadband microstrip ferromagnetic resonance (FMR), cavity FMR, and Brillouin light scattering spectroscopy techniques have been applied for detection and characterization of a magnetic inhomogeneity in a film sample. In the case of a 100 nm thick permalloy film, an additional magnetically depleted top sublayer has been detected due to pinning effect it produces on the magnetization in the bulk of the film. The pinning results in appearance of an exchange standing spin wave mode in the broadband FMR absorption spectrum, whose amplitudes are different depending on whether the film or the film substrate faces the microstrip transducer. Comparison of the experimental amplitudes for this mode with results of our theory for both film placements revealed that the depleted layer is located at the film surface facing away from the film substrate. Subsequent broadband FMR characterization of a large number of other presumably single-layer films with thicknesses in the range 30–100 nm showed the same result.

Sub-Doppler cooling with the 1 S 0 - 1 P 1 line in ytterbium

We demonstrate experimentally a strong plasmon-assisted enhancement of the transverse magneto-optical Kerr effect in permalloy gratings. The enhanced transverse magneto-optical Kerr effect is accompanied by an increased grating reflectivity with the maximum of enhancement being correlated with plasmonic Fano resonances. This correlation was confirmed by an intuitive Fano model and also through full-vectorial optical simulations. Simultaneously high reflectivity and transverse magneto-optical Kerr effect as well as narrowest ferromagnetic resonance linewidth and vanishing anisotropy make permalloy nanostructures attractive for applications in spintronics and nano-optics such as, for example, all-optical excitation of propagating spin waves and spectral tuning of optical nanoantennas.

Sub-Doppler cooling of ytterbium with the 1 S 0 – 1 P 1 transition including 171 Yb (I=1/2)

Multiple-post reentrant 3D lumped cavity modes have been realized to design the concept of a discrete Whispering Gallery and Fabry-Perot-like Modes for multimode microwave Quantum Electrodynamics experiments. Using the magnon spin-wave resonance of a submillimeter-sized Yttrium-Iron-Garnet sphere at millikelvin temperatures and a four-post cavity, we demonstrate the ultra-strong coupling regime between discrete Whispering Gallery Modes and a magnon resonance with a strength of 1.84 GHz. By increasing the number of posts to eight and arranging them in a D4 symmetry pattern, we expand the mode structure to that of a discrete Fabry-Perot cavity and modify the Free Spectral Range (FSR). We reach the superstrong coupling regime, where spin-photon coupling strength is larger than FSR, with coupling strength in the 1.1 to 1.5 GHz range.