Scanning Hall probe microscopy has been used to search for spontaneous fields at the well-defined edges of large mesoscopic disks, etched into the ab surface of very high quality single crystal Sr 2 RuO 4. Such fields are predicted to exist at locations of broken translational symmetry as a consequence of the proposed two-component spin-triplet chiral order parameterd = 0 (k x ± ik y)ẑ. We find no evidence for such fields and impose an upper limit of ±2.5 mG on their magnitude. We do, however, observe an abrupt apparent loss of strong bulk pinning and a change in the screening behavior above H ∼ 25 Oe. At high fields (H > 25 Oe) pronounced magnetic screening by the disks is very well described by a model containing only strong edge currents, and bulk critical currents do not appear to play a significant role. Our results are discussed in terms of relevant theoretical predictions.

Scanning Hall probe microscopy has been used to study vortex structures in very-high-quality single crystals of the unconventional superconductor Sr 2 RuO 4 (T c ∼ = 1.5 K). In none of our samples do we find credible evidence for the existence of the spontaneous fields or chiral domains predicted for the expected time-reversal symmetry-breaking order parameter. Even in our highest-quality samples we observe very strong vortex pinning and anomalous broadening of vortex profiles. The best samples also exhibit a clear field-driven triangular to square vortex lattice transition at low fields, as predicted by extended London theory calculations. In stark contrast, slightly less well-ordered samples exhibit pronounced vortex chaining/banding that we tentatively attribute to an extrinsic source of disorder.

cited By 125Many methods of analysing remotely sensed data assume that pixels are pure, and so a failure to accommodate mixed pixels may result in signi? cant errors in data interpretation and analysis. The analysis of data containing a large proportion of mixed pixels may therefore bene? t from the decomposition of the pixels into their component parts. Methods for unmixing the composition of pixels have been used in a range of studies and have often increased the accuracy of the analyses. However, many of the methods assume linear mixing and require end-member spectra, but mixing is often non-linear and end-member spectra are di? cult to obtain. In thispaper,an alternative approach to unmixing thecomposition of image pixels, which makes no assumptions about the nature of the mixing and does not require end-member spectra, is presented. The method is based on an arti? cial neural network (ANN) and shown in a case study to provide accurate estimates of sub-pixel land cover composition. The results of this case study showed that accurate estimates of the proportional cover of a class and its areal extent may be made. It was also shown that there was a tendency for the accuracy of the unmixing to increase with the complexity of the network and the intensity of training. The results indicate the potential to derive accurate information from remotely sensed data sets dominated by mixed pixels.Peer reviewe

Superconducting spintronics has emerged in the past decade as a promising new field that seeks to open a new dimension for nanoelectronics by utilizing the internal spin structure of the superconducting Cooper pair as a new degree of freedom 1,2 . Its basic building blocks are spin-triplet Cooper pairs with equally aligned spins, which are promoted by proximity of a conventional superconductor to a ferromagnetic material with inhomogeneous macroscopic magnetization 3 . Using low-energy muon spin-rotation experiments we find an unanticipated e ect, in contradiction with the existing theoretical models of superconductivity and ferromagnetism: the appearance of a magnetization in a thin layer of a non-magnetic metal (gold), separated from a ferromagnetic double layer by a 50-nm-thick superconducting layer of Nb. The e ect can be controlled either by temperature or by using a magnetic field to control the state of the remote ferromagnetic elements, and may act as a basic building block for a new generation of quantum interference devices based on the spin of a Cooper pair.The ability to manipulate the spin degree of freedom of charge carriers is key to realizing future spin-based electronics. Integrating superconductors into spintronic devices can greatly enhance performance 1 and allows the transport of spin over long distances without the dissipation of heat 2 . To achieve the alignment of electron spins, ferromagnetic materials are used. Superconductivity and ferromagnetism are, however, antagonistic states of matter, and the interplay between these two states results in the conversion of conventional spin-singlet into spin-triplet pair correlations 3 . Whereas spin-singlet pairs have spin angular momentum S = 0, spin-triplet pairs have S = 1, with three possible spin projections s z = −1, 0, +1. The realization of such spin-triplet pairs in mesoscopic systems containing interfaces between superconducting (S) and ferromagnetic (F) layers has attracted much interest from both the theoretical and experimental communities. Interaction of spin-singlet superconductivity with collinear ferromagnetism leads to oscillations and suppression of the pair correlation at a short distance ξ f due to the exchange magnetic field in the ferromagnet, which tends to align the spins of electrons parallel 4-7 . However, to create longer-range penetration of spin-triplet superconductivity into the ferromagnet, interaction with a non-collinear magnetism is required [8][9][10] , motivating the discovery of superconducting currents through ferromagnetic metals over distances far longer than the singlet penetration length ξ f (refs 11-13). These long-range triplet components (LRTC) have parallel spin projections (s z = ±1), and are not suppressed by the exchange field. Theory predicts that the conversion into spin-triplet pairs should also give rise to an induced magnetic moment in the superconductor, decaying away from the interface [14][15][16] , often called the inverse or magnetic proximity effect. For diffusive systems this induced m...

Late morbidity and death as a result of progressive coronary vascular obliteration remains a major unsolved problem after orthotopic heart transplantation. Various percutaneous catheter intervention (PCI) methods have been used to treat transplant coronary artery disease (CAD), but few reports have assessed the longitudinal results of these procedures. Of 1,440 cardiac transplant patients at University of California, Los Angeles, Medical Center, treated between 1984 and 2004, 65 patients who had undergone orthotopic heart transplantation underwent PCI on a total of 156 coronary artery lesions because of transplant CAD between July 1993 and August 2004. The procedural success rate was 93%. Angiographic follow-up was available for 42 patients and 101 lesions 9.5 ؎ 5.8 months after PCI. The global restenosis rate was 36%. Multivariate analysis was used to assess 49 clinical, angiographic, and immunologic variables per lesion. The use of a cutting balloon increased the risk of restenosis (odds ratio 11.5, p <0.01) and the use of stents decreased the risk of restenosis (odds ratio 0.34, p <0.05) compared with other PCI methods. The restenosis rate with drugeluting stents was 19%, lower than that with bare metal stents (31%). Of the 65 patients, 20 (31%) died within 1.9 ؎ 1.8 years after PCI. The actuarial survival rate was 56% at 5 years after the first PCI. In conclusion, although the restenosis rate after PCI was higher than that in nontransplant patients with CAD, the immediate and long-term results were acceptable in this high-risk population. Despite the intense inflammation associated with transplant CAD, drug-eluting stents appeared to reduce the occurrence of restenosis. Compared with historical controls, PCI may also improve the actuarial survival rate of patients undergoing orthotopic heart transplantation.