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Aladyshkin A. Yu. Andronov A. A. Pestov E. E. Nozdrin Yu. N. Kurin V. V. Cucolo A. M. Monaco R. Boffa M. 《Radiophysics and Quantum Electronics》2003,46(2):109-127
Using a local technique, we study the microwave radiation power P3(T,P,Hdc) at the triple frequency of the main signal as a function of the temperature T, the input power P, and the external magnetic field Hdc perpendicular to the superconductor surface for YBa2Cu3O7 (YBCO) films, monocrystals, and polycrystals and for Nb films. The most distinctive feature of the temperature dependence P3(T) of nonlinear response of superconductors is a maximum of the nonlinearity near the critical temperature Tc. Spatial distributions of the third-harmonic power are obtained for YBCO films at various temperatures. These distributions are indicative of a nonuniform distribution of Tc over the superconductor surface. Additional nonlinearity maxima are discovered in the dependence P3(T) for YBCO films and monocrystals at temperatures about 2Tc/3. These maxima are probably related to the existence of several superconducting phases with different critical temperatures. For Nb films, the second nonlinearity maximum in the dependence P3(T) appears only in the presence of an external magnetic field. The experimental data are interpreted within the framework of a two-fluid model of a superconductor, which takes into account the phenomenological nonlinear relationship between the vector potential A and the supercurrent js(A). The origin of nonlinearity in the studied superconductors is discussed. 相似文献
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A. Yu. Aladyshkin A. K. Vorob’ev P. P. Vysheslavtsev E. B. Klyuenkov A. S. Mel’nikov Yu. N. Nozdrin I. D. Tokman 《Journal of Experimental and Theoretical Physics》1999,89(5):940-947
The temperature dependence of the local energy barrier to formation of the mixed state in YBaCuO thin-film superconducting
samples has been determined. The measurement technique is based on use of a small ferromagnetic particle as the magnetic field
source. It is found that the energy barrier to creation of vortices (for the field oriented parallel to the CuO planes) is
anomalously small while the dependence of the corresponding threshold current j
c(T) differs substantially from the temperature dependence of the pair-breaking current. The experimental results are interpreted
in terms of the model of a Josephson medium. The observed temperature dependence of j
c points to a strong suppression of the superconducting order parameter at the intergrain boundaries, which for the most probable
type of boundaries: superconductor-insulator-superconductor, is evidence of anisotropic pairing.
Zh. éksp. Teor. Fiz. 116, 1735–1749 (November 1999) 相似文献
3.
A. Yu. Aladyshkin A. S. Mel’nikov D. A. Ryzhov A. V. Samokhvalov A. A. Fraerman W. Gillijns A. V. Silhanek V. V. Moshchalkov 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(1):3-7
The results of theoretical and experimental investigations of the peculiarities of the nucleation of superconductivity in the presence of a nonuniform magnetic field induced by ferromagnetic films or dots with out-of-plane magnetic anisotropy are reviewed. It is shown that the phase transition line of superconductor-ferromagnet hybrids in the H-T plane (H is an external magnetic field and T is temperature) is determined significantly by the spatial distribution of nonuniform magnetic field. It allows to control the thermodynamic and transport properties of superconductor-ferromagnet hybrids by tuning the magnetic state of the ferromagnet. 相似文献
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A. V. Putilov D. A. Muzychenko A. Yu. Aladyshkin 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2016,10(2):273-281
The initial stage of growth of nanoislands prepared by thermal deposition of niobium on the reconstructed surface of Si(111)-7 × 7 in ultrahigh vacuum is experimentally investigated. The morphological and electrophysical properties of niobium-based nanostructures are studied by means of low-temperature scanning tunneling microscopy and spectroscopy. It is found that upon the deposition of niobium on a substrate at room temperature, clusters and nanoislands are formed on the silicon surface, having a characteristic lateral size of 10 nm with the metallic type of tunneling conductivity at low temperatures. Upon the deposition of niobium on a heated substrate, quasi-one-dimensional (1D) and quasi-two-dimensional (2D) structures with typical lateral dimensions of up to 200 nm and three-dimensional pyramidal islands with semiconducting type of tunneling conductivity at low temperatures are formed. 相似文献
5.
D. A. Muzychenko A. I. Oreshkin S. I. Oreshkin S. S. Ustavschikov A. V. Putilov A. Yu. Aladyshkin 《JETP Letters》2017,106(4):217-222
The initial stage of the adsorption of Ge on an Au(111) surface was investigated. The growth and stability of the structures formed at the surface were studied by ultrahigh-vacuum low-temperature scanning tunneling microscopy and analyzed using density functional theory. It was established that the adsorption of single Ge atoms at the Au(111) surface at room temperature leads to the substitution of Au atoms by Ge atoms in the first surface layer. An increasing of surface coverage up to 0.2–0.4 monolayers results in the growth of an amorphous binary layer composed of intermixed Au and Ge atoms. It was shown that the annealing of the binary layer at a temperature of T s ? 500 K, as well as the adsorption of Ge on the Au(111) surface heated to T s ? 500 K for coverages up to 1 monolayer lead to a structural transition and the formation of an Au–Ge alloy at least in the first two surface layers. Based on experimental and theoretical data, it was shown that the formation of single-layer germanene on the Au(111) surface for coverages ≤1 monolayer in the temperature range of T s = 297–500 K is impossible. 相似文献
6.
Spectra of the differential tunneling conductivity for ultrathin lead films grown on Si(111) 7 × 7 single crystals with a thickness of 9 to 50 ML have been studied by low-temperature scanning tunneling microscopy and spectroscopy. The presence of local maxima of the tunneling conductivity is characteristic of such systems. The energies of maxima of the differential conductivity are determined by the spectrum of quantum-confined states of electrons in a metallic layer and, consequently, the local thickness of the layer. It has been shown that features of the microstructure of substrates, such as steps of monatomic height, structural defects, and inclusions of other materials covered with a lead layer, can be visualized by bias-modulation scanning tunneling spectroscopy. 相似文献
7.
Giant anisotropy of the resistance induced by magnetic domains in superconductor/ferromagnet hybrids
A.Yu. Aladyshkin J. Fritzsche V.V. Moshchalkov 《Physica C: Superconductivity and its Applications》2010,470(19):883-885
We experimentally studied the magnetoresistance of a superconducting Al microbridge fabricated on top of a ferromagnetic BaFe12O19 single crystal. Due to the presence of a one-dimensional domain structure in the ferromagnetic substrate, the superconducting critical temperature reaches its maximal value at the compensation field, |H|?B0, when superconductivity nucleates above magnetic domains of opposite polarity with respect to the applied magnetic field H (so-called reverse-domain superconductivity, B0 being the amplitude of the z-component of the nonuniform magnetic field). Such localized superconductivity makes it possible to transfer superconducting currents without dissipation only along the magnetic domains, leading to a pronounced anisotropy of the resistance of this system at low temperatures. 相似文献
8.
Ustavshchikov S. S. Aladyshkin A. Yu. Kurin V. V. Markelov V. A. El’kina A. I. Klushin A. M. Yunin P. A. Rogov V. V. Vodolazov D. Yu. 《Physics of the Solid State》2019,61(9):1675-1681
Physics of the Solid State - The temperature dependence of the linear electrodynamic response of thin-film superconductor (MoN)–normal metal (Al) hybrid structures with a high conductivity... 相似文献
9.
Gillijns W Aladyshkin AY Lange M Van Bael MJ Moshchalkov VV 《Physical review letters》2005,95(22):227003
Domain-wall superconductivity is studied in a superconducting Nb film placed between two ferromagnetic Co/Pd multilayers with perpendicular magnetization. The parameters of top and bottom ferromagnetic films are chosen to provide different coercive fields, so that the magnetic domain structure of the ferromagnets can be selectively controlled. From the dependence of the critical temperature Tc on the applied magnetic field H, we have found evidence for domain-wall superconductivity in this three-layered F/S/F structure for different magnetic domain patterns. The phase boundary, calculated numerically for this structure from the linearized Ginzburg-Landau equation, is in good agreement with the experimental data. 相似文献
10.
Levichev M. Yu. El’kina A. I. Bukharov N. N. Petrov Yu. V. Aladyshkin A. Yu. Vodolazov D. Yu. Klushin A. M. 《Physics of the Solid State》2019,61(9):1544-1548
Physics of the Solid State - Highly disordered thin films of niobium nitride and the specific features of the proximity effect in NbN (S)–aluminum (N) bilayers with a large resistivity ratio,... 相似文献
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