Magneto-optical circular dichroism properties of fept layers with perpendicular anisotropy

Magneto-optical techniques allow the investigation of the reversal process in magnetic surfaces and granular systems and of their electronic structure. In the case of magnetic metals and their surfaces the use of VIS or nIR lights allow to explore the interband and intrabands transitions that involves the 3d band. Due to the magneto-optical effect is related with the spin-orbit coupling, this technique is quite sensible to structural and chemical orders which determine also the magnetic anisotropy [1]. In this work we investigate the magneto-optical properties at different wavelengths of nanometric films based in epitaxial FePt and Fe-FePt bilayer that exhibit perpendicular anisotropy. Magnetic circular dichroism technique (MCD) is used because it allows to investigate the magneto-optical properties and the reversal process of the entire layers. FePt films of 10 nm were deposited by RF sputtering directly on a MgO (100) single-crystal in order to obtain the epitaxial growth. The growth was performed at substrate temperatures in the range 415?C and 430 ?C. The films were obtained by alternating the deposition of very thin Fe and Pt layers with nominal thickness of about 0.2 nm. The chosen ratio between the individual thickness corresponds to a nominal atomic composition of Fe53Pt47. The ordered L10 phase growths epitaxially [2] with the c-axis perpendicular to the substrate. Lower chemical order was observed in the film annealed at 430?C. On this film a second layer of 5 nm of Fe was deposited which constitutes the bilayer Fe-FePt. The MCD hysteresis loops at 1.7 K were recorded using different continuous lasers covering the VIS-nIR spectrum range (476 nm - 904 nm). Details of the experimental set-up are described in [3]. The MCD hysteresis loop of the FePt film annealed at 415?C and measured with a wavelength 476.5 nm is represented in the figure 1. A square hysteresis loop is observed with a negative saturation MCD (-5.3 mrad) for positive magnetic fields. The large squareness ratio, near 1, and the large coercive field of 2.9 T confirm the high quality of the ordered c-axis epitaxial film and the orientation of the easy axis in this direction. The shape of MCD hysteresis loop measured using 632.8 nm is very similar to the measured with 476.5 nm, but the saturation MCD is positive and approximately 5 times smaller (+1.18 mrad). In the figure 2 the MCD hysteresis of the Fe-FePt film measured with 514.5 nm, 632.8 nm and 904.0 nm are represented. The hysteresis loop measured with the blue beam exhibits positive MCD in the saturation while with the red and n-IR beams that values are negative. Moreover the absolute saturation MCD increases with the increase of the wavelength being 13.9 mrad, -20,6 mrad and -23,4 mrad for the beams with wavelength 514.5 nm, 632.8 nm and 904.0 nm, respectively. The obtained hysteresis indicate the presence of two critical field, HC1 ≈1.3 T and HC2 ≈0.64 T being the coercive field 0.13 T. The reversal process does not indicate a full exchange coupling between the hard and soft layers. In fact micromagnetic calculations [4] indicate that 5 nm Fe layer is a thick- ness for which decoupling could be possible. Finally the shape of the hysteresis loop measured with 514,5 nm is slightly different of the loops measured with largest wavelengths, which are equal. The MCD values measured with 514,5 nm in the magnetic field range between HC1 and HC2 are small- er than the measured with larger wavelength. This suggests that modification of the MO signal due to the change of the wavelength is not similar in the Fe and FePt layers. Comparing the results, quantitatively the Fe-FePt film shows largest MCD signal than the FePt film. This difference can be due to larger Fe contain but it is not enough for explain the differences. Moreover in the Fe-FePt film the MCD changes from positive to negative values for largest wavelengths and the absolute MCD increases. The opposite behaviours are observed in the FePt film. Spectroscopic measurements are in progress to clarify these results. [1] A. Cebollada et al. Phys. Rev. B 50 (1994) 3419; H. Ebert,G.Y. Guo, G. Sch?tz IEEE Trans. Magn. 31 (1995) 3301. [2] F. Casoli, et al. IEEE Trans. Magn. 41 (2005) 3223. [3] L. Cavigli et al. J. Magn. Magn. Mater. 316 (2007) 798. [4] G. Asti et al. Phys. Rev. B 73 (2006) 09440

Dielectric Effects in FeO x-Coated Au Nanoparticles Boost the Magnetoplasmonic Response: Implications for Active Plasmonic Devices

Plasmon resonance modulation with an external magnetic field (magnetoplasmonics) represents a promising route for the improvement of the sensitivity of plasmon-based refractometric sensing. To this purpose, an accurate material choice is needed to realize hybrid nanostructures with an improved magnetoplasmonic response. In this work, we prepared core@shell nanostructures made of an 8 nm Au core surrounded by an ultrathin iron oxide shell (≤1 nm). The presence of the iron oxide shell was found to significantly enhance the magneto-optical response of the noble metal in the localized surface plasmon region, compared with uncoated Au nanoparticles. With the support of an analytical model, we ascribed the origin of the enhancement to the shell-induced increase in the dielectric permittivity around the Au core. The experiment points out the importance of the spectral position of the plasmonic resonance in determining the magnitude of the magnetoplasmonic response. Moreover, the analytical model proposed here represents a powerful predictive tool for the quantification of the magnetoplasmonic effect based on resonance position engineering, which has significant implications for the design of active magnetoplasmonic devices

Tailoring nanostructured surfaces with plasmonic/magnetic multifunctional response

IIn this work, we present an innovative way to functionalize large surfaces combining both plasmonic and magnetic nanoparticles on a substrate, by the growth of bilayers and a subsequent single annealing. In particular, we show here the formation of Au and gamma- Fe₂O₃ nanoparticles using this route. Thermal treatments promote the nanostructuration of the film plus a partial oxidation of Fe to form ferrimagnetic oxides. For this purpose, annealing conditions and the structure of the bilayer must be selected to achieve an optimal nanostructuration, avoiding the full oxidation of Fe to form antiferromagnetic hematite. Published by AIP Publishing

Communication of pharmacogenetic research results to HIV-infected treated patients: standpoints of professionals and patients.

International audienceThe aim of pharmacogenetic studies is to adapt therapeutic strategies to individual genetic profiles, thus maximising their efficacy and minimising the likelihood of adverse side effects. Since the advent of personalised medicine, the issue of communicating research results to participants has become increasingly important. We addressed this question in the context of HIV infection, as patients and associations are particularly concerned by research and therapeutic advances. We explored the standpoints of both research professionals and participants involved in a pharmacogenetic study conducted in a cohort of HIV-infected patients. The setting of the research protocol was followed over a 2-year period. Participants' standpoints were collected through a questionnaire and interviews were conducted with research professionals. Of 125 participants, 76% wished to receive individual results and 71% wished to receive collective results; 39% did not know when results might be expected. Communication of global research results is a principle that is generally accepted by professionals. Concerning individual feedback, the professionals felt that it was necessary if it could be of direct benefit to the participant, but they expressed doubts for situations with no recognised benefit. Our results highlight the necessity to consider this issue in greater detail. We suggest the need to anticipate the debates concerning individual feedback, to differentiate between situations and the importance of further investigations on the opportunities and modalities of communication. Finally, our work emphasised the opposite pressures between the pursuit of scientific knowledge and the therapeutic orientation of clinical trials

Height and timing of growth spurt during puberty in young people living with vertically acquired HIV in Europe and Thailand.

OBJECTIVE: The aim of this study was to describe growth during puberty in young people with vertically acquired HIV. DESIGN: Pooled data from 12 paediatric HIV cohorts in Europe and Thailand. METHODS: One thousand and ninety-four children initiating a nonnucleoside reverse transcriptase inhibitor or boosted protease inhibitor based regimen aged 1-10 years were included. Super Imposition by Translation And Rotation (SITAR) models described growth from age 8 years using three parameters (average height, timing and shape of the growth spurt), dependent on age and height-for-age z-score (HAZ) (WHO references) at antiretroviral therapy (ART) initiation. Multivariate regression explored characteristics associated with these three parameters. RESULTS: At ART initiation, median age and HAZ was 6.4 [interquartile range (IQR): 2.8, 9.0] years and -1.2 (IQR: -2.3 to -0.2), respectively. Median follow-up was 9.1 (IQR: 6.9, 11.4) years. In girls, older age and lower HAZ at ART initiation were independently associated with a growth spurt which occurred 0.41 (95% confidence interval 0.20-0.62) years later in children starting ART age 6 to 10 years compared with 1 to 2 years and 1.50 (1.21-1.78) years later in those starting with HAZ less than -3 compared with HAZ at least -1. Later growth spurts in girls resulted in continued height growth into later adolescence. In boys starting ART with HAZ less than -1, growth spurts were later in children starting ART in the oldest age group, but for HAZ at least -1, there was no association with age. Girls and boys who initiated ART with HAZ at least -1 maintained a similar height to the WHO reference mean. CONCLUSION: Stunting at ART initiation was associated with later growth spurts in girls. Children with HAZ at least -1 at ART initiation grew in height at the level expected in HIV negative children of a comparable age

The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14 happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov 2017 (this is the "post-print" and "post-proofs" version; minor corrections only from v1, and most of errors found in proofs corrected

A protective personal factor against disability and dependence in the elderly: an ordinal regression analysis with nine geographically-defined samples from Spain

Background Sense of Coherence (SOC) is defined as a tendency to perceive life experiences as comprehensible, manageable and meaningful. The construct is split in three major domains: Comprehensibility, Manageability, and Meaningfulness. SOC has been associated with successful coping strategies in the face of illness and traumatic events and is a predictor of self-reported and objective health in a variety of contexts. In the present study we aim to evaluate the association of SOC with disability and dependence in Spanish elders. Methods A total of 377 participants aged 75 years or over from nine locations across Spain participated in the study (Mean age: 80.9 years; 65.3% women). SOC levels were considered independent variables in two ordinal logistic models on disability and dependence, respectively. Disability was established with the World health Organization-Disability Assessment Schedule 2.0 (36-item version), while dependence was measured with the Extended Katz Index on personal and instrumental activities of daily living. The models included personal (sex, age, social contacts, availability of an intimate confidant), environmental (municipality size, access to social resources) and health-related covariates (morbidity). Results High Meaningfulness was a strong protective factor against both disability (Odds Ratio [OR] = 0.50; 95% Confidence Interval [CI] = 0.29–0.87) and dependence (OR = 0.33; 95% CI = 0.19–0.58) while moderate and high Comprehensibility was protective for disability (OR = 0.40; 95% CI = 0.22–0.70 and OR = 0.39; 95%CI = 0.21–0.74), but not for dependence. Easy access to social and health resources was also highly protective against both disability and dependence. Conclusions Our results are consistent with the view that high levels of SOC are protective against disability and dependence in the elderly. Elderly individuals with limited access to social and health resources and with low SOC may be a group at risk for dependence and disability in Spain.This project was partially funded by a research contract in support of the project “Epidemiological Study of Dementia in Spain” signed by the Pfizer Foundation and Carlos III Institute of HealthS

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO