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Abstract The proximity effect between superconductors and ferromagnets may become long range due to the generation of triplet pairs. The recent finding of a long, one micron-range unconventional Josephson effect between YBa2Cu3O7 ...
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Abstract The proximity effect between superconductors and ferromagnets may become long range due to the generation of triplet pairs. The recent finding of a long, one micron-range unconventional Josephson effect between YBa2Cu3O7 high Tc cuprates separated by a half metallic La0.7Sr0.3MnO3 manganite ferromagnet has uncovered a novel unconventional triplet proximity effect. In this paper, we examine the temperature dependence of the critical current in planar Josephson junctions. We find that the critical current—normal resistance product follows the predictions of traditional superconductor-normal metal-superconductor junctions, which implies that triplet pairs in a ferromagnet are transported in the diffusive limit similarly to singlet pairs in a normal metal. This result calls for theoretical studies of the new triplet Josephson effect and underlines its potential in future superconducting spintronics.
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Abstract Ferromagnetic resonance (FMR) spectroscopy measurements were performed on NbRe/Co/NbRe trilayers in order to probe spin pumping across the superconductor/ferromagnet interface and to detect the possible presence of spin-t...
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Abstract Ferromagnetic resonance (FMR) spectroscopy measurements were performed on NbRe/Co/NbRe trilayers in order to probe spin pumping across the superconductor/ferromagnet interface and to detect the possible presence of spin-triplet pairing in the superconducting NbRe layer. FMR spectra were acquired as a function of frequency, magnetic field, and temperature, and reveal that the Gilbert damping parameter associated with spin pumping remains almost constant as temperature goes down through the superconducting transition. Additionally, the dependence of the Gilbert damping parameter on the thickness of the NbRe layer in trilayers is used to determine the values of the spin mixing conductance at the interface ( 18?21 ?nm?2) and the spin diffusion length ( 7.1?12.5 nm) in the NbRe layer. These findings may suggest that spin pumping would still be effective even though NbRe becomes superconducting, which would indicate that the spin-triplet would be the dominant pairing mechanism. Future experiments are proposed in light of these results.
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A system containing four alternating ferromagnetic and superconducting layers (F-1/S-1/F-2/S-2) is examined in this work. The state of this contact may be controlled by an external magnetic field. The critical temperature of the s...
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A system containing four alternating ferromagnetic and superconducting layers (F-1/S-1/F-2/S-2) is examined in this work. The state of this contact may be controlled by an external magnetic field. The critical temperature of the superconducting transition and the Josephson current are calculated theoretically at different thicknesses and collinear orientations of magnetizations of ferromagnetic layers. It is demonstrated that this F-1/S-1/F-2/S(2)system may serve as a controllable Josephson 0-pi contact or an inverse spin valve.
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The electrical resistivity and magnetization of half-metallic/ superconducting La0.7Sr0.3MnO3/Bi2Sr2CaCu2O8 (LSMO/Bi-2212) heterostructures are investigated with the thickness of Bi-2212 top layer fixed at 50 nm and that of the LS...
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The electrical resistivity and magnetization of half-metallic/ superconducting La0.7Sr0.3MnO3/Bi2Sr2CaCu2O8 (LSMO/Bi-2212) heterostructures are investigated with the thickness of Bi-2212 top layer fixed at 50 nm and that of the LSMO underlayer (t) being 40, 80 and 160 nm. Both the normal state resistivity ρ(290 K) and the superconducting transition width (δTC) increase with increasing t. On the other hand, the superconducting transition onset temperature (Tcon) of Bi-2212 monotonically decreases with increasing t, which is attributed to pair breaking via the polarized spins from the ferromagnetic LSMO due to strengthening of the magnetization. However, the rate of reduction of Tcon in Bi-2212 with respect to the thickness of LSMO is found to be much less in LSMO(t)/Bi-2212 compared with that of YBCO in the analogous system PCMO(t)/YBCO. From the qualitative analysis of the electrical and magnetic data we conclude that growing domains enhancing the magnetization is the reason for the thickness-dependent suppression of superconductivity in LSMO(t)/Bi-2212 bi-layers.
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With a view to meeting the requirements of high resolution microelectromechanical system applications, we studied high resolution (submicron scale) and high aspect ratio pattern fabrication through x-ray lithography. As a critical...
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With a view to meeting the requirements of high resolution microelectromechanical system applications, we studied high resolution (submicron scale) and high aspect ratio pattern fabrication through x-ray lithography. As a critical part of the x-ray lithography, an x-ray mask should have the properties of high resolution and being a thick absorber. To decrease the scattering effect, a 100 keV e-beam lithography system was used for the fabrication of the high resolution x-ray mask. 3 mum thick PMMA (polymethylmethacrylate) resist was patterned and 2 mum thick gold was electroplated onto the patterned resist to form the x-ray mask. Scanning electron microscopy analysis showed that the sidewall and pattern uniformity were sufficient and that the proximity effect did not play a significant role for the selected test patterns. 6 mum thick PMMA resist was exposed by the x-ray mask; the experimental results proved the feasibility of reproducing submicron features. 0.5 mum nested patterns with an aspect ratio of 12 were fabricated by this approach.
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Background It remains unclear whether total gastrectomy is necessary for patients with proximal T2/T3 gastric cancer. To explore the oncological safety of proximal gastrectomy for proximal T2/T3 gastric cancer, in this study, we e...
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Background It remains unclear whether total gastrectomy is necessary for patients with proximal T2/T3 gastric cancer. To explore the oncological safety of proximal gastrectomy for proximal T2/T3 gastric cancer, in this study, we evaluated the metastatic rates in and the therapeutic effect of dissection of key distal lymph node stations that are usually excluded in proximal gastrectomy. Methods In this study, we examined 202 patients seen between January 2000 and December 2012, who underwent total gastrectomy with lymph node dissection (D1/D1+/D2; 2/17/183) and was pathologically diagnosed as T2/T3 gastric cancer exclusively located in the upper third of the stomach. The theoretical therapeutic necessity of dissecting lymph nodes at each lymph node station was evaluated based on the therapeutic index calculated by multiplying the frequency of metastasis at each station and the 5-year survival rate of patients with metastasis to that station. Results The 5-year overall survival rate (95% confidence interval) was 72.9% (65.5-80.3). The metastatic rates at #4d and #12a were very low (0.99% and 0.006%, respectively), and those at #5 and #6 were zero, and therapeutic indices for #4d, #5, #6 and #12a were zero. On the other hand, the most frequent metastatic station was #3, followed by #1, #2 and #7 (overall metastatic rate > 12%), which was consistent with the order of the therapeutic indices. Conclusions Considering the nodal stations that need to be dissected, proximal gastrectomy would be the choice and oncologically safe for patients with T2/T3 proximal gastric cancer.
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We consider the Josephson effect in a three-layer symmetric superconductorferromagnet- superconductor (SFS) system. In the framework of the proximity effect theory we calculate the Josephson current as a function of the ferromagne...
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We consider the Josephson effect in a three-layer symmetric superconductorferromagnet- superconductor (SFS) system. In the framework of the proximity effect theory we calculate the Josephson current as a function of the ferromagnet thickness, taking into account the Umklapp processes at the internal boundary and the critical temperature dependence of the order parameter phase difference. The results of the calculations are in good agreement with experimental data.
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Meissner effect in the diffusive normal metal/insulator/s-wave superconductor junctions is studied in the presence of the magnetic impurities for various situations, where we have used the Usadel equation with Nazarov's generalize...
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Meissner effect in the diffusive normal metal/insulator/s-wave superconductor junctions is studied in the presence of the magnetic impurities for various situations, where we have used the Usadel equation with Nazarov's generalized boundary condition. It is shown that the susceptibility of the diffusive normal metal for s-wave superconductor is almost independent of the height of the insulating barrier at the interface. (c) 2005 Elsevier B.V. All rights reserved.
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A general coupled surface integral equation formulation and a numerical solution procedure have been employed for the analysis of systems of multiple parallel conductors of general cross sections over a relatively wide frequency r...
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A general coupled surface integral equation formulation and a numerical solution procedure have been employed for the analysis of systems of multiple parallel conductors of general cross sections over a relatively wide frequency range. The conductors are excited by a transverse magnetic (TM_z) plane wave. Results for resistance and internal reactance for systems of multiple circular and rectangular conductors have been obtained, and the proximity effect has also been studied for multiconductor systems by comparing the cases of different spacings between conductors. The proximity effect causes both the resistance and the internal reactance of the outer conductors to increase and causes the resistance and internal reactance of the inner conductors to decrease at moderately high frequencies.
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A proximity-effect thermometer measures the temperature dependent critical supercurrent in a long superconductor--normal metal--superconductor (SNS) Josephson junction. Typically, the transition from the superconducting to the nor...
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A proximity-effect thermometer measures the temperature dependent critical supercurrent in a long superconductor--normal metal--superconductor (SNS) Josephson junction. Typically, the transition from the superconducting to the normal state is detected by monitoring the appearance of a voltage across the junction. We describe a new approach to detect the transition based on the temperature increase in the resistive state due to Joule heating. Our method increases the sensitivity and is especially applicable for temperatures below about 300 mK.
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