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KY Fan 《Linear and Multilinear Algebra》1988,23(4):283-284
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KY Fan 《Linear and Multilinear Algebra》1973,1(1):1-4
Inequalities concerning real square matrices A with positive definite symmetric component A+A*are derived from certain inertia relations which hold for any complex (not necessarily real) square matrices A with positive definite
A+A* 相似文献
A+A* 相似文献
4.
A.?V.?Zaitsev G.?A.?Ovsyannikov K.?Y.?Constantinian Yu.?V.?Kislinski? A.?V.?Shadrin I.?V.?Borisenko P.?V.?Komissinskiy 《Journal of Experimental and Theoretical Physics》2010,110(2):336-344
It is shown experimentally that the superconducting current density in Nb/Au/Ca1 − x
Sr
x
CuO2/YBa2Cu3O7 − δ hybrid superconducting heterostructures with a Ca1 − x
Sr
x
CuO2 anti-ferromagnetic (AF) cuprate interlayer is anomalously high for interlayer thicknesses d
M
= 10–50 nm and the characteristic damping length for superconducting correlations is on the order of 10 nm. The experimental
results are explained on the basis of theoretical analysis of a junction of two superconductors (S′ and S) connected by a
magnetic multilayer with the AF ordering of magnetization in the layers. It is shown that with such a magnetization ordering,
anomalous proximity effect determined by the singlet component of the condensate wavefunction may take place. As a result,
the critical currents in S′/I/AF/S and S′/I/N/S structures (I denotes an insulator, and N, the normal metal) may coincide
in order of magnitude even when the thickness of the AF interlayer considerably exceeds the decay length of the condensate
wavefunction in ferromagnetic layers. 相似文献
5.
G. A. Ovsyannikov Yu. V. Kislinskii K. Y. Constantinian A. V. Shadrin V. V. Demidov A. M. Petrzhik 《Journal of Experimental and Theoretical Physics》2017,124(4):628-634
We have studied the current transport and magnetism in epitaxial hybrid superconducting mesa structures consisting of a cuprate superconductor and superconducting niobium with a manganite LaMnO3 (LMO) interlayer. We have shown experimentally using magnetic resonance that the magnetization, magnetic anisotropy parameters, and transition temperature to the ferromagnetic state of the interlayer of the structures are analogous to those of an autonomous LMO film grown on a neodymium gallate substrate. The estimate of the barrier height obtained from the dependence of the characteristic resistance of mesa structures on the interlayer thickness has shown the barrier height variation with the thickness in the range of 5–30 mV. The temperature dependences of the conductivity of the mesa structure in the range between superconducting transition temperatures of the superconductors can be described in the theory taking into account the d-wave nature of the superconductivity for one of the electrodes and the spin-filtering of carriers passing through the tunnel interlayer. Spin-filtering is confirmed by the tunnel magnetoresistance and the high sensitivity of mesa structures to a weak external magnetic field in a voltage interval smaller than the gap of niobium. 相似文献
6.
Temperature Dependence of the Voltage Induced by Spin Current in a Manganite–Iridate Heterostructure
Shaikhulov T. A. Stankevich K. L. Constantinian K. Y. Demidov V. V. Ovsyannikov G. A. 《Physics of the Solid State》2021,63(10):1532-1535
Physics of the Solid State - The temperature dependence of the voltage induced by spin current is studied in the epitaxial thin-film La0.7Sr0.3MnO3/SrIrO3 heterostructure deposited on a... 相似文献
7.
G. A. Ovsyannikov V. V. Demidov Yu. N. Khaydukov L. Mustafa K. Y. Constantinian A. V. Kalabukhov D. Winkler 《Journal of Experimental and Theoretical Physics》2016,122(4):738-747
A heterostructure that consists of the YBa2Cu3O7–δ cuprate superconductor and the SrRuO3/La0.7Sr0.3MnO3 ruthenate/manganite spin valve is investigated using SQUID magnetometry, ferromagnetic resonance, and neutron reflectometry. It is shown that a magnetic moment is induced due to the magnetic proximity effect in the superconducting part of the heterostructure, while the magnetic moment in the composite ferromagnetic interlayer is suppressed. The magnetization emerging in the superconductor coincides in order of magnitude with the results of calculations taking into account the induced magnetic moment of Cu atoms because of orbital reconstruction at the interface between the superconductor and the ferromagnet, as well as with the results of the model taking into account the variations in the density of states at a distance on the order of the coherence length in the superconductor. The experimentally obtained characteristic penetration depth of the magnetic moment in the superconductor considerably exceeds the coherence length of the cuprate superconductor, which indicates the predominance of the mechanism of induced magnetic moment of Cu atoms. 相似文献
8.
G. A. Ovsyannikov A. E. Sheyerman A. V. Shadrin Yu. V. Kislinskii K. Y. Constantinian A. Kalabukhov 《JETP Letters》2013,97(3):145-148
The superconducting current induced by the penetration of the long-range triplet component of superconducting correlations into a composite ferromagnetic interlayer has been detected in mesa-heterostructures based on oxide cuprate superconductors YBa2Cu3O7 ? δ and Au/Nb bilayer films with the composite oxide interlayer that is made of ferromagnetic films of manganite La0.7Sr0.3MnO3 and ruthenate SrRuO3 and has a thickness much larger than the length of correlations determined by the exchange field. The deviation of the superconducting current in the mesa-heterostructure with the fraction of the second harmonic of 13% from a sinusoidal current-phase relation has been detected; this deviation can also be due to the generation of the triplet component of superconducting correlations in the ferromagnet. 相似文献
9.
K. Y. Constantinian Yu. V. Kislinskii G. A. Ovsyannikov A. V. Shadrin A. E. Sheyerman A. L. Vasil’ev M. Yu. Presnyakov P. V. Komissinskiy 《Physics of the Solid State》2013,55(3):461-465
The structural, X-ray diffraction, and electrophysical studies of hybrid superconducting hetero-structures with an interlayer of cuprate antiferromagnetic Ca1 ? x Sr x CuO2 (CSCO) with the upper electrode Nb/Au and the lower electrode YBa2Cu3O7 ? δ (YBCO) have been carried out. It has been experimentally shown that the epitaxial growth of two cuprates, YBCO and CSCO, results in the formation of an interface on which the enrichment of the CSCO interlayer with charge carriers proceeds to a depth of about 20 nm. In this case, the conduction of the enriched CSCO region proves to be closer to metallic, whereas the CSCO film deposited onto the NdGaO3 substrate is a Mott insulator with hopping conduction. 相似文献
10.
Komissinskiy P Ovsyannikov GA Borisenko IV Kislinskii YV Constantinian KY Zaitsev AV Winkler D 《Physical review letters》2007,99(1):017004
Josephson coupling between an s- and d-wave superconductor through a 50 nm thick Ca1-xSrxCuO2 antiferromagnetic layer was observed for the hybrid Nb/Au/Ca1-xSrxCuO2/YBa2Cu3O7-delta heterostructures and investigated as a function of temperature, magnetic field, and applied millimeter-wave electromagnetic radiation. The magnetic field dependence of the supercurrent I(c)(H) exhibits anomalously rapid oscillations, which is the first experimental evidence of the theoretically predicted giant magneto-oscillations in Josephson junctions with antiferromagnetic interlayers. 相似文献