Surface spin waves in thin permalloy films are studied by means of propagative-spin-wave spectroscopy. We observe a systematic difference of up to several tens of MHz when comparing the frequencies ...of counterpropagating waves. This frequency nonreciprocity effect is modeled using an analytical dipole-exchange theory that considers the mutual influence of nonreciprocal spin wave modal profiles and differences in magnetic anisotropies at the two film surfaces. At moderate film thickness (20 nm and below), the frequency nonreciprocity scales linearly with the wave vector and quadratically with the thickness, whereas a more complex nonmonotonic behavior is observed at larger thickness. Our paper suggests that surface wave frequency nonreciprocity can be used as an accurate spectroscopic probe of magnetic asymmetries in thin ferromagnetic films.
•A microwave to optical photon converter is proposed.•Its application field is Quantum Information.•The converter is based on travelling magnons in a thin magnetic film.•The conversion is achieved ...through coupling of magnons to guided optical modes.•The conversion efficiency for this device is evaluated theoretically.
In this work, we propose a concept of a microwave to optical photon converter for applications in Quantum Information (QI) that is based on travelling magnons in a thin magnetic film. The converter employs an epitaxially grown Bi-substituted yttrium iron garnet (Bi-YIG) film as the medium for propagation of travelling magnons (spin waves). The conversion is achieved through coupling of magnons to guided optical modes of the film. We evaluate the conversion efficiency for this device theoretically. Our prediction is that it will be larger by at least four orders of magnitude than experimentally obtained in a similar process exploiting a uniform magnetization precession mode in a YIG sphere. By creating an optical resonator of a large length from the film (such that the traveling magnon decays before forming a standing wave over the resonator length) one will be able to further increase the efficiency by several orders of magnitude, potentially reaching a value similar to achieved with opto-mechanical resonators.
An important advantage of the suggested concept of the QI devices based on travelling spin waves is a perfectly planar geometry compatible with the optical lithography process and a possibility of implementing the device as a hybrid opto-microwave chip.
Brillouin light scattering (BLS), complemented by ferromagnetic resonance (FMR) characterization, has been used for studying spin-wave (SW) propagation in Py(L)/Pt(6-mn) bilayers of various Py ...thicknesses (4mn < or = L < or = 10 nm). The FMR measurements allowed determination of the pertinent magnetic parameters and revealed the existence of a normal surface anisotropy. A pronounced asymmetry of Damon-Eshbach (DE) wave frequencies has been evidenced by BLS. Therefore, the difference between Stokes and anti-Stokes DE frequencies has been measured versus SW wave number for all the samples. A detailed discussion about the origin of this frequency difference is reported, which concludes that this is due to interface Dzyaloshinskii-Moriya interaction (IDMI).
We show that periodic magnetic nanostructures represent a perfect system for studying excitations on disordered periodical lattices because of the possibility of controlled variation of the degree of ...disorder by varying the applied magnetic field. Magnetic force microscopy images and ferromagnetic resonance (FMR) data collected inside minor hysteresis loops for a periodic array of Permalloy nanowires were used to demonstrate correlation between the type of FMR response and the degree of disorder of the magnetic ground state.
PDF
