V. Golub - Academia.edu (original) (raw)

Papers by V. Golub

The Zn-paratacamite family, ZnxCu4−x(OH)6Cl2 for x ≥ 0.33, is an ideal system for studying spin-1... more The Zn-paratacamite family, ZnxCu4−x(OH)6Cl2 for x ≥ 0.33, is an ideal system for studying spin-1 2 frustrated magnetism in the form of antiferromagnetic Cu 2+ kagome planes. Here we report a new synthesis method by which high quality millimeter-sized single crystals of Zn-paratacamite have been produced. These crystals have been characterized by metal analysis, x-ray diffraction, neutron diffraction, and thermodynamic measurements. The x = 1 member of the series displays a magnetic susceptibility that is slightly anisotropic at high temperatures with χc > χ ab . Neutron and synchrotron x-ray diffraction experiments confirm the quality of these x = 1 single crystals and indicate no obvious structural transition down to temperatures of T = 2 K.

Shape memory and ferromagnetic shape memory effects in single-crystal Ni 2 MnGa thin films

Journal of Alloys and Compounds - J ALLOYS COMPOUNDS, 2008

It was established a substantial decrease of the output magnetization-induced SHG for the 7ns Erb... more It was established a substantial decrease of the output magnetization-induced SHG for the 7ns Erbium glass laser (λ=1535nm) with pulse repetition about 20Hz for Yttrium Garnett alloy derivatives. For the study we have used circularly polarised light of the Q-switched the Nd-YAG laser (λ=1064nm) with pulse energy about 20mJ. We have studied derivatives of iron garnett films deposited on the crystalline Gd3Ga5O12 (111) substrates. The experiment was done for the diagonal xx SHG components, where the direction x corresponds to the crystallographic x-axis in the Gd3Ga5O12 (111) substrate plane. Varying the direction of the applied magnetic filed by sign it was established that magnetic contrast determining the SHG difference for two opposite magnetic field directions disappears at pump power of the circularly polarized light equal to about 0.6GW/cm2.

Physical Review Letters, 2006

We have investigated the electronic transport properties of the triple-layered ruthenate Sr4Ru3O1... more We have investigated the electronic transport properties of the triple-layered ruthenate Sr4Ru3O10. We observed surprising anomalous features near its itinerant metamagnetic transition, including ultrasharp magnetoresistivity steps, a nonmetallic temperature dependence in resistivity for upward field sweeps, and a resistivity drop in temperature dependence for downward field sweeps. These features suggest that the metamagnetic transition of Sr4Ru3O10 occurs via an electronic phase separation process with magnetic domain formation.

Physical Review B, 2012

We performed ferromagnetic resonance measurements of square arrays of noninteracting Permalloy ci... more We performed ferromagnetic resonance measurements of square arrays of noninteracting Permalloy circular dots for different orientations of external magnetic field with respect to the patterned film plane (θ). Out-of-plane angular dependence of the main resonance peak was measured in the whole range of the field angles 0 • θ 90 • . The main eigenmodespatial distribution is strongly nonuniform due to the dot nonellipsoidal shape. Nevertheless, for dots with small aspect ratio b = L/R 0.1 (where R is dot radius and L is dot thickness) Kittel's equation, assuming uniform dynamic magnetization (no pinning at the dot lateral edges), describes the peak position with high accuracy. Analytical calculations and micromagnetic simulations confirmed the gradual evolution of the main mode profile and a smooth transition from the strong to relatively weak pinning conditions with the change of external magnetic field angle.

Journal of Physics and Chemistry of Solids, 2004

We report the size-dependent magneto-optical properties of nanometer-sized magnetite particles em... more We report the size-dependent magneto-optical properties of nanometer-sized magnetite particles embedded in poly(methyl methacrylate). The nanocomposite material contains Fe3O4 particles with diameters ranging from 8 to 200 nm. Faraday rotation spectra are measured in the wavelength range of 400–900 nm. A broad spectral band centered at 650 nm (1.91eV) is observed in the for the larger (200 nm) particles. Decreasing

Journal of Nanoscience and Nanotechnology, 2012

We report magnetic, dynamic and transport properties of discontinuous metal-insulator multilayers... more We report magnetic, dynamic and transport properties of discontinuous metal-insulator multilayers Fe/MgO grown on amorphous Corning ® glass and single-crystalline MgO (001) substrates. The films of structure Substrate/MgO (3 nm)/[Fe (0.6 nm)/MgO (3.0 nm)]×10 were prepared in ultra-high vacuum conditions using Pulsed Laser Deposition. It was shown that conditions of epitaxial growth are favorable for MgO substrates. As a result a substantial increase of tunneling magnetoresistance caused by spin-filtering effect was observed and reasonably theoretically explained. The value of TMR ∼ 9.2% at room temperature in 18 kOe magnetic field is three times higher comparing to that for the samples grown on Corning ® glass substrates.

Journal of Applied Physics, 2005

The influence of substrate temperature and annealing conditions on structure, magnetic, and magne... more The influence of substrate temperature and annealing conditions on structure, magnetic, and magnetotransport properties of NiMnGa films was investigated, and the crucial effect of substrate temperature was confirmed. It was found that amorphous disordered films are formed during deposition on a substrate held at room temperature. Postdeposition annealing leads to partial recrystallization and recovery of magnetic properties. Annealing at 773 K does not allow the formation of crystal structure, which is created during deposition on substrates held at the same temperature. The highest values of magnetoresistance were observed in the films with a well-defined crystal structure.

Journal of Applied Physics, 2013

Spin wave spectra of 40-nm thick perpendicularly magnetized circular Permalloy dots of 250 nm rad... more Spin wave spectra of 40-nm thick perpendicularly magnetized circular Permalloy dots of 250 nm radius were measured using ferromagnetic resonance technique in 70-80 GHz range at 4.2 K and in 10 GHz at room temperature. The five sharp resonance peaks were observed for both frequency ranges. The resonance fields can be well described by a magneto-exchange dispersion relation, implying that the observed resonances correspond to circular "drumhead" modes with Bessel-function profiles. The relative distances between neighbor peaks for different frequency ranges were almost the same, while the absolute interpeak distances in millimeter range were $30% bigger than at 10 GHz, as predicted by the theory. V C 2013 American Institute of Physics. [http://dx.