Giant magnetoresistance of iron-chromium superlattices at microwaves

Interaction between an rf electromagnetic field and the Fe/Cr superlattice placed in a rectangular waveguide so that a high-frequency current passes in the plane of superlattice layers is considered. The transmission coefficient versus the magnetic field strength is found at centimeter waves, and a correlation between this dependence and the field dependence of the dc magnetoresistance is established. It is shown that a change in the transmission coefficient may greatly exceed the giant magnetoresistance of the superlattice. The frequency dependence of the microwave measurements has an oscillatory character. The oscillation frequencies are analyzed in terms of wavelet transformation. Two types of oscillation periods are found to exist, one of which corresponds to the resonance of waves traveling in the superlattice along the direction parallel to the narrow wall of the waveguide.     

Microwave Giant Magnetoresistance and Ferromagnetic and Spin-Wave Resonances in (CoFe)/Cu Nanostructures

Journal of Experimental and Theoretical Physics - The microwave phenomena that occur in magnetic multilayer (CoFe)/Cu nanostructures, which have a giant magnetoresistance, are studied. The...     

The Giant Magnetoresistance Effect in Microwave Reflection from (CoFe)/Cu Superlattices

Technical Physics - Experiments on the giant magnetoresistance effect observed in microwave reflection have been conducted in the frequency range of 26–38 GHz on (CoFe)/Cu superlattices...     

Analysis of the space-time dynamics of acoustic fields on the surface of a solid

The space-time dynamics of an acoustic field produced by a piezoelectric transducer in a pulsed mode is studied. The detection of acoustic fields is achieved using a Doppler laser interferometer. It is shown that, for a pictorial representation of the dynamics of a pulsed process, it is convenient to use the patterns of instantaneous spatial field distributions within the scanning area, the observation of which at successive instants makes it possible to trace the acoustic field variations on a time scale considerably smaller than the period of the ultrasonic wave. Experimental data demonstrating the process of phase propagation along the sample boundary as a function of time are presented. They are in good agreement with theoretical results obtained by using various methods of acoustic field calculation and different scalar potential distributions over the transducer surface. It is shown that the velocity of phase propagation along the sample boundary, which is mainly determined by the wave front curvature of the elastic wave incident on the sample surface, can considerably exceed the wave velocity in the unbounded medium.     

Quality Characterization of CVD-Synthesized Graphene Films by Scanning Probe Microscopy

Doklady Physics - The problem of efficiency of using electrical properties for characterizing graphene structures obtained by chemical vapor deposition and formed on substrates of various materials...     

Resonance Variations of the Microwave Refractive Index in YIG Plates

Technical Physics - The influence of microwave resonance phenomena on complex refractive index in YIG plates has been theoretically and experimentally studied in the frequency range 26–38...     

Determination of the Effective Magnetic Permeability of Nanocomposite Media

Doklady Physics - In this work, the method of determination of the effective magnetic permeability is considered for composite media containing magnetic particles in the form of general ellipsoids...     

Optical, magnetic, and dielectric properties of opal matrices with intersphere nanocavities filled with crystalline multiferroic, piezoelectric, and segnetoelectric materials

The properties and structure of composites on the basis of the lattice packings of SiO₂ nanospheres (opal matrices), containing in intersphere nanocavities clusters of the crystal phases of multiferroics and piezoelectric and ferroelectric materials.     

Extraction of signals from white and colored noise using the discrete wavelet transform

Methods based on wavelet analysis are used to study longitudinal elastic waves propagating in aluminum single crystals in the [111] and [001] directions at frequencies of 5 and 10 MHz. Results of the wavelet filtering of responses of the laser Doppler interferometer to these acoustic signals are reported. The efficiency of filtering the time dependencies of the interferometer response in the presence of white and colored noise is studied. Recommendations concerning the choice of the filtering parameters are given.