Double percolation effects and fractal behavior in magnetic/superconducting hybrids

Perpendicular magnetic anisotropy ferromagnetic/ superconducting (FM/SC) bilayers with a labyrinth domain structure are used to study nucleation of superconductivity on a fractal network, tunable through magnetic history. As clusters of reversed domains appear in the FM layer, the SC film shows a percolative behavior that depends on two independent processes: the arrangement of initial reversed domains and the fractal geometry of expanding clusters. For a full labyrinth structure, the behavior of the upper critical field is typical of confined superconductivity on a fractal network.Comment: 15 pages, 5 figure

Perpendicular magnetic anisotropy in Nd-Co alloy films nanostructured by di-block copolymer templates

et al.Nd-Co amorphous magnetic films with perpendicular magnetic anisotropy have been grown on nanostructured templates prepared with self-organized di-block poly(styrene)-block-poly(4-vinylpyridine) copolymer layers with a periodic structure of 60 nm spaced pores. These templates modify both the magnetic film topography and mechanical strain on a local scale. The effect of these structural changes is particularly noticeable in the low thickness range of the magnetic films where the transition from in-plane to out-of plane magnetization takes place. The Nd-Co films grown on the copolymer template present lower perpendicular magnetic anisotropy and, also, stronger stripe domain pinning effects in comparison with reference films grown on flat Si substrates. © 2012 American Institute of Physics.Work supported by Spanish MEC under Grants FIS2008-06249 and Consolider CSD2007-00010 and by CAM under Grant S2009/MAT-1726.Peer Reviewe

Double percolation effects and fractal behavior in magnetic/superconducting hybrids

Perpendicular magnetic anisotropy ferromagnetic/superconducting (FM/SC) bilayers with a labyrinth domain structure are used to study nucleation of superconductivity on a fractal network, tunable through magnetic history. As clusters of reversed domains appear in the FM layer, the SC film shows a percolative behavior that depends on two independent processes: the arrangement of initial reversed domains and the fractal geometry of expanding clusters. For a full labyrinth structure, the behavior of the upper critical field is typical of confined superconductivity on a fractal network

2D magnetic domain wall ratchet: The limit of submicrometric holes

The study of ratchet and crossed-ratchet effects in magnetic domain wall motion through 2D arrays of asymmetric holes is extended in this article to the submicrometric limit in hole size (small size regime). Therefore, the gap has been closed between the 2D ratchets in the range of tens-of-micrometers (large size regime) and the small size regime 1D ratchets based on nanowires. The combination of Kerr microscopy, X-ray PhotoEmission Electron Microscopy and micromagnetic simulations has allowed a full magnetic characterisation of both the domain wall (DW) propagation process over the whole array and the local DW morphology and pinning at the holes. It is found that the 2D small size limit is driven by the interplay between DW elasticity and half vortex propagation along hole edges: as hole size becomes comparable to DW width, flat DW propagation modes are favoured over kinked DW propagation due to an enhancement of DW stiffness, and pinned DW segments adopt asymmetric configurations related with Néel DW chirality. Nevertheless, both ratchet and crossed-ratchet effects have been experimentally found, and we propose a new ratchet/inverted-ratchet effect in the submicrometric range driven by magnetic fields and electrical currents respectively

Adenomyosis is an independent risk factor for complications in deep endometriosis laparoscopic surgery

Deep endometriosis (DE) occurs in 15-30% of patients with endometriosis and is associated with concomitant adenomyosis in around 25-49% of cases. There are no data about the effect of the presence of adenomyosis in terms of surgical outcomes and complications. Thus, the aim of the present study was to evaluate the impact of adenomyosis on surgical complications in women with deep endometriosis undergoing laparoscopic surgery. A retrospective cohort study including women referred to the endometriosis unit of a referral teaching hospital. Two expert sonographers preoperatively diagnosed DE and adenomyosis. DE was defined according to the criteria of the International Deep Endometriosis Analysis group. Adenomyosis was considered when 3 or more ultrasound criteria of the Morphological Uterus Sonographic Assessment group were present. Demographical variables, current medical treatment, symptoms, DE location, surgical time, hospital stay and difference in pre and post hemoglobin levels were collected. The Clavien-Dindo classification was used to assess surgical complications, and multivariate analysis was performed to compare patients with and without adenomyosis. 157 DE patients were included into the study; 77 (49.05%) had adenomyosis according to transvaginal ultrasound (TVS) and were classified in the A group, and 80 (50.95%) had no adenomyosis and were classified in the noA group. Adenomyosis was associated with a higher rate of surgical complications: 33.76% (A group) vs. 12.50% (noA group) (p?<?0.001). Multivariate analysis showed a 4.56-fold increased risk of presenting complications in women with adenomyosis (CI 1.90-11.30; p?=?0.001) independently of undergoing hysterectomy. There was a statistically significant association between the number of criteria of adenomyosis present in each patient and the proportion of patients presenting surgical complications (p?<?0.001). Adenomyosis is an independent preoperative risk factor for surgical complications in DE surgery after adjustment for known demographic, clinical and surgical risk factors.© 2022. The Author(s)

Topologically protected superconducting ratchet effect generated by spin-ice nanomagnets

We have designed, fabricated and tested a robust superconducting ratchet device based on topologically frustrated spin ice nanomagnets. The device is made of a magnetic Co honeycomb array embedded in a superconducting Nb film. This device is based on three simple mechanisms: (i) the topology of the Co honeycomb array frustrates in-plane magnetic configurations in the array yielding a distribution of magnetic charges which can be ordered or disordered with in-plane magnetic fields, following spin ice rules; (ii) the local vertex magnetization, which consists of a magnetic half vortex with two charged magnetic Neel walls; (iii) the interaction between superconducting vortices and the asymmetric potentials provided by the Neel walls. The combination of these elements leads to a superconducting ratchet effect. Thus, superconducting vortices driven by alternating forces and moving on magnetic half vortices generate a unidirectional net vortex flow. This ratchet effect is independent of the distribution of magnetic charges in the array

Investigation of the Impact of Distributed Generation on Power System Protection

Integration of Distributed Generation (DG) on distribution networks has a positive impact which includes the following: low power losses, improved utility system reliability and voltage improvement at buses. A real distribution network is radial in which energy flow is unidirectional from generation to transmission and from distribution to the load. However, when a DG is connected to it, the power flow becomes bidirectional, and the protection setting of the network may be affected. Therefore, the aim of this research work is to investigate the impact of distributed generation DG on power system protection. The test distribution network is first subjected to load flow analysis to determine its healthiness with and without DG connection. The load flow results confirm that the integration of the DG into the distribution network reduces the active power load loss by 92.68% and improves voltage profiles at each bus of the network by 90.72%. Thereafter, the impact of DG on the protection setting of the existing test network was investigated. Integrating DGs to the network, from our result, shows an increase in the fault currents, which in turn caused false tripping, nuisance tripping, and blinding of protection relay compared with when DGs are not connected. The protection relays were reset at the point of common coupling (PCC) to prevent any abnormal tripping. This is the major contribution of the research wor