Hybrid heterostructures with superconducting/antiferromagnetic interfaces

We report on structural, DC, X-ray and neutron studies of hybrid superconducting mesa-heterostructures with a cuprate antiferromagnetic interlayer Ca1-xSrxCuO2 (CSCO). The upper electrode was bilayer Nb/Au superconductor and copper oxide superconductor YBa2Cu3O7 (YBCO) was the bottom electrode. It was experimentally shown that during the epitaxial growth of the two films YBCO and CSCO a charge carrier doping takes place in the CSCO interlayer with a depth about 20 nm. The conductivity of the doped part of CSCO layer is close to the metal type, while the reference CSCO film, deposited directly on NdGaO3 substrate, behaves as Mott insulator with the hopping conductivity. The interface Au/CSCO is clearly seen on bright-field image of the cross-section of heterostructure and gives the main contribution to the total resistance of mesa-heterostructure.Comment: 16 pages, 9 figure

Evidence for spin-triplet superconducting correlations in metal-oxide heterostructures with non-collinear magnetization

Heterostructures composed of ferromagnetic La0.7Sr0.3MnO3, ferromagnetic SrRuO3, and superconducting YBa2Cu3Ox were studied experimentally. Structures of composition Au/La0.7Sr0.3MnO3/SrRuO3/YBa2Cu3Ox were prepared by pulsed laser deposition, and their high quality was confirmed by X-ray diffraction and reflectometry. A non-collinear magnetic state of the heterostructures was revealed by means of SQUID magnetometry and polarized neutron reflectometry. We have further observed superconducting currents in mesa-structures fabricated by deposition of a second superconducting Nb layer on top of the heterostructure, followed by patterning with photolithography and ion-beam etching. Josephson effects observed in these mesa-structures can be explained by the penetration of a triplet component of the superconducting order parameter into the magnetic layers.Comment: 10 pages, 6 figure

Josephson Effect in Hybrid Oxide Heterostructures with an Antiferromagnetic Layer

Josephson coupling between an s- and d-wave superconductor through a 50 nm thick Ca(1-x)Sr(x)CuO(2) antiferromagnetic layer was observed for the hybrid Nb/Au/Ca(1-x)Sr(x)CuO(2) /YBa(2)Cu(3)O(7-d

Josephson Effect in Hybrid Oxide Heterostructures with an Antiferromagnetic Layer

Josephson coupling between an s- and d-wave superconductor through a 50 nm thick Ca(1-x)Sr(x)CuO(2) antiferromagnetic layer was observed for the hybrid Nb/Au/Ca(1-x)Sr(x)CuO(2) /YBa(2)Cu(3)O(7-d

Electron transport in hybrid superconductor heterostructures with manganite interlayers

Hybrid herostructures comprising an YBa(2)Cu(3)O (x) (YBCO) high-temperature superconductor (HTS) layer and Nb/Au low-temperature superconductor (LTS) bilayer (with critical HTS and LTS temperatures T (c) and T'(c), respectively), separated by a thin (d (M) = 5-20 nm) interlayer of LaMnO(3), La(0.7)Ca(0.3)MnO(3), or La(0.7)Sr(0.3)MnO(3) manganite have been studied. The electric resistance and magnetic properties of individual (evaporated directly onto the substrate) manganite films and related hybrid herostructures have been measured. Based on quasi-classical equations, analytical expressions for the conductivity of herostructures at T a parts per thousand currency sign T'(c) are obtained in the case of a low-transparency superconductor/manganite interface. It is established that the conductivity of heterostructures is determined by the proximity effect (related to the penetration of a condensate wavefunction from the Nb/Au bilayer to manganite) and depends strongly on interface transparency. At low temperatures (T a parts per thousand(a) T (c)'), the conductivity peaks are found at voltages determined by the exchange field of the manganite interlayer. At T (c)' < T < T (c), conductivity features at nearly zero bias voltages are observed, which are related to the superconductivity of the YBCO electrode

Interfaces in superconducting hybrid heterostructures with an antiferromagnetic interlayer

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 Y(B)a(2)Cu(3)O(7 - delta) (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

Microwave dynamics of Josephson structures with nontrivial current-phase relation

The electrophysical and dynamic parameters (Shapiro steps and detector response) of hybrid heterostructures based on oxide superconductors with the d-wave symmetry of the order parameter are studied. Deviation of the current-phase relation from the trivial (sinusoidal) form is revealed. It is shown in terms of a generalized Resistive Shunted Function model with the junction capacitance and higher harmonics of the current-phase relation has virtually no influence on the width of harmonic Shapiro steps but changes the scale of the step-width dependence on the ac current of an external electromagnetic field. In addition, it is shown that these dependences have no local minima if the current-phase relation (CPR) contains harmonics higher than the first. For heterostructures, the amplitudes and signs of the CPR harmonics are determined through comparison of theoretical and experimental data