P. M. Vetoshko

Optical excitation of spin waves in epitaxial iron garnet films: MSSW vs BVMSW.

In most of the previous studies of the spin wave optical generation in magnetic dielectrics, the backward volume spin waves were excited. Here we modified the parameters of the circularly polarized optical pump beams emitted by femtosecond laser to reveal surface spin waves in bismuth iron garnet thin film. Beams that are larger than 10 μm in diameter generate both surface and volume spin waves with only one spectral peak near the ferromagnetic resonance. On the contrary, narrower beams excite predominantly surface spin waves of higher frequency, providing an additional peak in the spin wave spectrum. Thus different interference patterns of the magnetization dynamics are achievable. This may significantly broaden the capabilities of spin wave based devices.

The effect of the disk magnetic element profile on the saturation field and noise of a magneto-modulation magnetic field sensor

Using the finite element method, it was shown by simulations that the approximation of a semielliptic thickness profile of magnetic disk by a stepped profile reduces the saturation field. Reducing the saturation field improves the sensitivity of magneto-modulation sensors, which is confirmed by experiments in the measurements of noise using magnetic field sensors that have a core with a stepped profile. The obtained level of magnetic sensor noise with a four-stage-core profile (1.5 × 10−9 Oe/Hz1/2) is more than an order of magnitude lower than in the known modern counterparts.

Flux-gate magnetic field sensor based on yttrium iron garnet films for magnetocardiography investigations

A new type of f lux-gate vector magnetometer based on epitaxial yttrium iron garnet films has been developed and constructed for magnetocardiography (MCG) investigations. The magnetic field sensor can operate at room temperature and measure MCG signals at a distance of about 1 mm from the thoracic cage. The high sensitivity of the sensor, better than 100 fT/Hz1/2, is demonstrated by the results of MCG measurements on rats. The main MCG pattern details and R-peak on a level of 10 pT are observed without temporal averaging, which allows heart rate anomalies to be studied. The proposed magnetic sensors can be effectively used in MCG investigations.

The magnetic field sensor based on the longitudinal magnetophotonic effect in a magnetoplasmonic crystal

Nowadays creation of high-sensitive magnetic sensors is of great interest for many applications.

Role of elastic dissipation in the formation of the resonant properties of magnetization precession in the magnetoelastic environment

A set of coupled magnetoelastic equations is used to examine the problem concerning the establishment of free magnetization oscillations under the condition that dissipation is lacking in the magnetic system. The critical relationship between elastic damping parameters and the magnetoelasticity constant, which corresponds to the minimum in the dependence of magnetic damping on elastic one, is found. The bellshaped peak, on both sides of which the influence of an elastic system on the magnetic one diminishes, is detected in the dependence between the effective magnetic oscillation damping parameter and the elastic oscillation damping parameter. The observed phenomena is suggested to interpret using the model of two (magnetic and elastic) oscillators coupled through magnetoelastic interaction. The given model makes it possible to reveal four regimes of steady-state oscillations: weak damping with beats, strong damping without beats, weak damping without beats, and supercritical exponential growth. The mechanical similarity of observed phenomena is discussed, and recommendations needed to organize experiments are proposed.

Vector magneto-optical sensor based on transparent magnetic films with cubic crystallographic symmetry

The concept of vector magneto-optical magnetometry is proposed and experimentally demonstrated. The key element of the vector magnetometer is a transparent high Faraday activity magnetic film with a cubic crystal lattice. Magnetocrystalline anisotropy of the film leads to the three dimensional trajectory of the film magnetization when the magnetization is rotated by the control magnetic field. It makes the magnetization sensitive to all three components of the external magnetic field. This field can be found from the harmonic composition of the Faraday rotation dependence on the azimuth angle of the control magnetic field. The demonstrated vector magnetometer is promising for mapping and visualization of ultra small magnetic fields.

The Role of Elastic Dissipation in the Formation of Magnetization Precession in Magnetoelastic Medium

As applied to the problem of reducing the noise of a rotational magnetometer, the formation of damping of magnetization precession due to elastic dissipation in magnetoelastic medium is considered. It is shown that, at a large enough elastic dissipation, the effectiveness of its contribution to the magnetic dissipation sharply decreases.