Controlling spin pumping into superconducting Nb by proximity-induced spin-triplet Cooper pairs

Proximity-induced long-range spin-triplet supercurrents, important for the field of superconducting spintronics, are generated in superconducting/ferromagnetic heterostructures when interfacial magnetic inhomogeneities responsible for spin mixing and spin flip scattering are present. The multilayer stack Nb/Cr/Fe/Cr/Nb has been shown to support such currents when fabricated into Josephson junction devices. However, creating pure spin currents controllably in superconductors outside of the Josephson junction architecture is a bottleneck to progress. Recently, ferromagnetic resonance was proposed as a possible direction, the signature of pure supercurrent creation being an enhancement of the Gilbert damping below the superconducting critical temperature, but the necessary conditions are still poorly established. Here, we demonstrate that pumping pure spin currents into a superconductor in the presence of an external magnetic field is only possible when conditions supporting proximity-induced spin-triplet effects are satisfied. Our study is an important step forward for pure spin supercurrent creation, considerably advancing the field of superconducting spintronics

Spin transport parameters of NbN thin films characterized by spin pumping experiments

We present measurements of ferromagnetic resonance driven spin pumping and inverse spin Hall effect in NbN/Y3Fe5O12 (YIG) bilayers. A clear enhancement of the (effective) Gilbert damping constant of the thin-film YIG was observed due to the presence of the NbN spin sink. By varying the NbN thickness and employing spin-diffusion theory, we have estimated the room-temperature values of the spin-diffusion length and the spin Hall angle in NbN to be 14 nm and −1.1×10−2, respectively. Furthermore, we have determined the spin mixing conductance of the NbN/YIG interface to be 10nm−2. The experimental quantification of these spin transport parameters is an important step towards the development of superconducting spintronic devices involving NbN thin films

Emergent Phenomena Induced by Spin-Orbit Coupling at Surfaces and Interfaces

Spin-orbit coupling (SOC) describes the relativistic interaction between the spin and momentum degrees of freedom of electrons, and is central to the rich phenomena observed in condensed matter systems. In recent years, new phases of matter have emerged from the interplay between SOC and low dimensionality, such as chiral spin textures and spin-polarized surface and interface states. These low-dimensional SOC-based realizations are typically robust and can be exploited at room temperature. Here we discuss SOC as a means of producing such fundamentally new physical phenomena in thin films and heterostructures. We put into context the technological promise of these material classes for developing spin-based device applications at room temperature

The diagnostic value of endoscopy and Helicobacter pylori tests for peptic ulcer patients in late post-treatment setting

BACKGROUND: Guidelines for management of peptic ulcer patients after the treatment are largely directed to detection of H. pylori infection using only non-invasive tests. We compared the diagnostic value of non-invasive and endoscopy based H. pylori tests in a late post-treatment setting. METHODS: Altogether 34 patients with dyspeptic complaints were referred for gastroscopy 5 years after the treatment of peptic ulcer using a one-week triple therapy scheme. The endoscopic and histologic findings were evaluated according to the Sydney classification. Bacteriological, PCR and cytological investigations and (13)C-UBT tests were performed. RESULTS: Seventeen patients were defined H. pylori positive by (13)C-UBT test, PCR and histological examination. On endoscopy, peptic ulcer persisted in 4 H. pylori positive cases. Among the 6 cases with erosions of the gastric mucosa, only two patients were H. pylori positive. Mucosal atrophy and intestinal metaplasia were revealed both in the H. pylori positive and H. pylori negative cases. Bacteriological examination revealed three clarithromycin resistant H. pylori strains. Cytology failed to prove validity for diagnosing H. pylori in a post-treatment setting. CONCLUSIONS: In a late post-treatment setting, patients with dyspepsia should not be monitored only by non-invasive investigation methods; it is also justified to use the classical histological evaluation of H. pylori colonisation, PCR and bacteriology as they have shown good concordance with (13)C-UBT. Moreover, endoscopy and histological investigation of a gastric biopsy have proved to be the methods with an additional diagnostic value, providing the physician with information about inflammatory, atrophic and metaplastic lesions of the stomach in dyspeptic H. pylori positive and negative patients. Bacteriological methods are suggested for detecting the putative antimicrobial resistance of H. pylori, aimed at successful eradication of infection in persistent peptic ulcer cases

Interactions of nanorod particles in the strong coupling regime

The plasmon coupling in a nanorod dimer obeys the exponential size dependence according to the Universal Plasmon Ruler Equation. However, it was shown recently that such a model does not hold at short nanorod distance (Nano Lett. 2009, 9, 1651). Here we study the nanorod coupling in various cases, including nanorod dimer with the asymmetrical lengths and symmetrical dimer with the varying gap width. The asymmetrical nanorod dimer causes two plasmon modes: one is the attractive lower- energy mode and the other the repulsive high-energy mode. Using a simple coupled LC-resonator model, the position of dimer resonance has been determined analytically. Moreover, we found that the plasmon coupling of symmetrical cylindrical (or rectangular) nanorod dimer is governed uniquely by gap width scaled for the (effective) rod radius rather than for the rod length. A new Plasmon Ruler Equation without using the fitting parameters has been proposed, which agrees well with the FDTD calculations. The method has also been extended to study the plasmonic wave-guiding in a linear chain of gold nanorod particles. A field decay length up to 2700nm with the lateral mode size about 50nm (~wavelength/28) has been suggested.Comment: 31 pages, 6 figures, 58 reference