GHz sandwich strip inductors based on Fe-N Films

Planar strip inductors consisting of two Fe-N films enclosing a conducting film made of Cu, were fabricated on oxidized Si substrates. The inductors were 1mm long, 2 to 100 um wide, with layers of thickness ~0.1 um for the magnetic films and ~0.5 um for the conductor. The soft (Hc=4-8 Oe) magnetic layers were biased during impedance measurement by applying an external field along the strip length thereby facilitating the transverse susceptibility configuration. Biased strips exhibited 70 to 100% inductance enhancement at 1GHz with quality factors Q=4.5 to 3, respectively. The magnetic contribution to the total flux in the narrow devices was less than predicted theoretically, which was attributed to hardening of the magnetic material at the edges of the strip, where the deposition was close to 60 degree incidence. Test films were fabricated on tilted substrates and found to develop a very high anisotropy (up to 1 kOe) for deposition angles larger than 30 degrees. Optimizing the flux closure at the strip edges and using thicker conductor layers is essential for further improving the performance of sandwich strip inductors.Comment: 18 pages, 9 figure

Spin flip scattering at Al surfaces

Non-local measurements are performed on a multi terminal device to $in-situ$ determine the spin diffusion length and in combination with resistivity measurements also the spin relaxation time in Al films. By varying the thickness of Al we determine the contribution to spin relaxation from surface scattering. From the temperature dependence of the spin diffusion length it is established that the spin relaxation is impurity dominated at low temperature. A comparison of the spin and momentum relaxation lengths for different thicknesses reveals that the spin flip scattering at the surfaces is weak compared to that within the bulk of the Al films.Comment: 11 pages, 5 figure

Coulomb Blockade and Coherent Single-Cooper-Pair Tunneling in Single Josephson Junctions

We have measured the current-voltage characteristics of small-capacitance single Josephson junctions at low temperatures (T < 0.04 K), where the strength of the coupling between the single junction and the electromagnetic environment was controlled with one-dimensional arrays of dc SQUIDs. We have clearly observed Coulomb blockade of Cooper-pair tunneling and even a region of negative differential resistance, when the zero-bias resistance of the SQUID arrays is much higher than the quantum resistance h/e^2 = 26 kohm. The negative differential resistance is evidence of coherent single-Cooper-pair tunneling in the single Josephson junction.Comment: RevTeX, 4 pages with 6 embedded figure

Enhanced spin accumulation in a superconductor

A lateral array of ferromagnetic tunnel junctions is used to inject and detect non-equilibrium quasi-particle spin distribution in a superconducting strip made of Al. The strip width and thickness is kept below the quasi particle spin diffusion length in Al. Non-local measurements in multiple parallel and antiparallel magnetic states of the detectors are used to in-situ determine the quasi-particle spin diffusion length. A very large increase in the spin accumulation in the superconducting state compared to that in the normal state is observed and is attributed to a diminishing of the quasi-particle population by opening of the gap below the transition temperature.Comment: 6 pages, 4 figures; accepted for publication in Journal of Applied Physic

Spin injection and relaxation in a mesoscopic superconductor

We study spin accumulation and spin relaxation in a superconducting nanowire. Spins are injected and detected by using a set of magnetic tunnel contact electrodes, closely spaced along the nanowire. We observe a giant enhancement of the spin accumulation of up to five orders of magnitude on transition into the superconducting state, consistent with the expected changes in the density of states. The spin relaxation length decreases by an order of magnitude from its value in the normal state. These measurements combined with our theoretical model, allow us to distinguish the individual spin flip mechanisms present in the transport channel. Our conclusion is that magnetic impurities rather than spin-orbit coupling dominate spin-flip scattering in the superconducting state.Comment: 5 pages, 5 figure

Integration of patient-reported outcome measures with key clinical outcomes after immediate latissimus dorsi breast reconstruction and adjuvant treatment

Background: linical evidence on patient-reported outcome measures (PROMS) in breast reconstruction is lacking. The aim of this study was to evaluate PROMs in implant-assisted latissimus dorsi (LDI) or tissue-only autologous latissimus dorsi (ALD) flap reconstruction in relation to complications and adjuvant treatments.Methods: this was a prospective cohort study involving six UK centres. Eligible patients had primary early-stage breast cancer. The European Organization for Research and Treatment of Cancer quality-of-life questionnaire (QLQ)-C30 and QLQ-BR23, Functional Assessment of Cancer Therapy—Breast Cancer scale (FACT-B), Body Image Scale, and Hospital Anxiety and Depression Scale were completed before operation and at 3, 6 and 12 months after surgery.Results: a total of 182 patients (82 LDI and 100 ALD) were recruited between 2007 and 2010 with symptomatic (59·9 per cent) or screen-detected (39·6 per cent) cancers. Some 64·3 per cent had lymph node-negative disease; 30 per cent of the LDI group had radiotherapy, compared with 53·0 per cent in the ALD group (P = 0·004). Early complications up to 3 months after surgery were reported in 66 and 51·0 per cent of patients in the LDI and ALD groups respectively (P = 0·062) and long-term complications (4–12 months) in 48 and 45·0 per cent (P = 0·845). Role functioning and pain (P = 0·002 for both) were adversely affected in the ALD group compared with results in the LDI group, with no significant effects of radiotherapy on any health-related quality of life (HRQL). Chemotherapy and early complications adversely affected HRQL, which improved between 3 and 12 months after surgery (P &lt; 0·010 for all).Conclusion: there is evidence of similar HRQL between types of latissimus dorsi breast reconstruction for up to a year after surgery. There appear to be no overarching effects for radiotherapy after mastectomy on the specific HRQL domains studied in the short term. The identification of variables that affect HRQL is important, including their integration into the analysis of PROM

Diode Effect in Asymmetric Double Tunnel Barriers with Single Metal Nanoclusters

Asymmetric double tunnel barriers with the center electrode being a metal cluster in the quantum regime are studied. The zero dimensionality of the clusters used and the associated quantized energy spectra are manifest in well-defined steps in the current voltage characteristic (IVC). Record high current rectification ratios of 10000 for tunneling through such clusters are demonstrated at room temperature. We are able to account for all of the experimentally observed features by modeling our double barrier structures using a combination of discrete states and charging effects for tunneling through quantum dots.Comment: 8 pages and 3 figures. Accepted for publication in Applied Physics Letters in 15 march 200

Observation of shot-noise-induced asymmetry in the Coulomb blockaded Josephson junction

We have investigated the influence of shot noise on the IV-curves of a single mesoscopic Josephson junction. We observe a linear enhancement of zero-bias conductance of the Josephson junction with increasing shot noise power. Moreover, the IV-curves become increasingly asymmetric. Our analysis on the asymmetry shows that the Coulomb blockade of Cooper pairs is strongly influenced by the non-Gaussian character of the shot noise.Comment: 4 pages, 5 figures, RevTE

Phase-Charge Duality of a Josephson junction in a fluctuating electromagnetic environment

We have measured the current-voltage characteristics of a single Josephson junction placed in a high impedance environment. The transfer of Cooper pairs through the junction is governed by overdamped quasicharge dynamics, leading to Coulomb blockade and Bloch oscillations. Exact duality exists to the standard overdamped phase dynamics of a Josephson junction, resulting in a dual shape of the current-voltage characteristic, with current and voltage changing roles. We demonstrate this duality with experiments which allow for a quantitative comparison with a theory that includes the effect of fluctuations due to finite temperature of the electromagnetic environment