Propiedades magnetoeléctricas de una memoria magnetorresistiva basada en películas de FeCoNi/TiN/FeCoNi

[ES] Se ha diseñado un dispositivo de memoria para la grabación y lectura de información basado en el efecto de la anisotropía magnetorresistiva de una multicapa fabricada por sputtering mediante diodo de rf. El elemento de memoria se compone de tres películas delgadas, de composición Fe15Co20Ni65(160Å)/ TiN(50Å)/Fe15Co20Ni65(160Å). El dispositivo permite procesos de grabación y lectura estables, y se compone de 32 elementos de memoria rectangulares por columna, donde cada elemento tiene dimensiones de ¿m lo que permite la fabricación de memorias integradas con capacidades del orden de 106 bits. Se han ensayado elementos de memoria rectangulares de diferentes tamaños, con las esquinas redondeadas con objeto de conseguir procesos de lectura-escritura lo más estable posible. Se han analizado comparativamente los efectos de magnetorresistencia y magnetoimpedancia de los elementos de memoria de diferentes dimensiones. Sugerimos que la disminución del valor absoluto de la magnetoimpedancia del elemento de memoria es consecuencia de la reducción de la parte real, de origen magnetorresistivo.[EN] A miniaturised memory device for information recording and readout processes have been designed on the basis of anisotropic magnetoresistive effect in Fe15Co20Ni65(160Å)/ TiN(50Å)/Fe15Co20Ni65(160Å) three-layered film done by rf diode sputtering. Stable recording and readout processes were available for 32 rectangular element column, where each element had ¿m dimensions convenient to fabricate memory chip with 106 bits capacity. Rectangles of different sizes with removed corners were used in order to define the geometry of most of all stable recording and readout processes. Magnetoresistance and magnetoimpedance effects of a magnetic memory device have been comparatively analysed. We suggest that the decrease of the absolute value of the magnetoimpedance of the memory device comes from the reduction of the real part via the magnetoresistance.Dr. G.V.Kurlyandskaya acknowledges the financial support of the Basque Government. The work has been supported by the Basque Government under the project N PI97/113 and Spanish CICYT under project MAT-98/965. We thank J. L. Muñoz for helpful discussion.Kurlyandskaya, G.; Barandiarán García, JM.; García Miquel, ÁH.; Vázquez Vilalabeitia, M.; Vaskovskiy, V.; Svalov, A. (2000). High frequency and magnetoelectrical properties of magnetoresistive memory element based on FeCoNi/TiN/FeCoNi film. Boletín de la Sociedad Española de Cerámica y Vidrio. 39(4):581-583. https://doi.org/10.3989/cyv.2000.v39.i4.824S58158339

Ab initio evaluation of the charge-ordering in α′NaV2O5\alpha^\prime NaV_2O_5

We report {\it ab initio} calculations of the charge ordering in $\alpha^\prime NaV_2O_5$ using large configurations interaction methods on embedded fragments. Our major result is that the $2p_y$ electrons of the bridging oxygen of the rungs present a very strong magnetic character and should thus be explicitly considered in any relevant effective model. The most striking consequence of this result is that the spin and charge ordering differ substantially, as differ the experimental results depending on whether they are sensitive to the spin or charge density.Comment: 4 page

Proposal of an extended t-J Hamiltonian for high-Tc cuprates from ab initio calculations on embedded clusters

A series of accurate ab initio calculations on Cu_pO-q finite clusters, properly embedded on the Madelung potential of the infinite lattice, have been performed in order to determine the local effective interactions in the CuO_2 planes of La_{2-x}Sr_xCuO_4 compounds. The values of the first-neighbor interactions, magnetic coupling (J_{NN}=125 meV) and hopping integral (t_{NN}=-555 meV), have been confirmed. Important additional effects are evidenced, concerning essentially the second-neighbor hopping integral t_{NNN}=+110meV, the displacement of a singlet toward an adjacent colinear hole, h_{SD}^{abc}=-80 meV, a non-negligible hole-hole repulsion V_{NN}-V_{NNN}=0.8 eV and a strong anisotropic effect of the presence of an adjacent hole on the values of the first-neighbor interactions. The dependence of J_{NN} and t_{NN} on the position of neighbor hole(s) has been rationalized from the two-band model and checked from a series of additional ab initio calculations. An extended t-J model Hamiltonian has been proposed on the basis of these results. It is argued that the here-proposed three-body effects may play a role in the charge/spin separation observed in these compounds, that is, in the formation and dynamic of stripes.Comment: 24 pages, 4 figures, submitted to Phys. Rev.

Ab initio evaluation of local effective interactions in α′NaV2O5\alpha^\prime NaV_2O_5

We will present the numerical evaluation of the hopping and magnetic exchange integrals for a nearest-neighbor $t-J$ model of the quarter-filled $\alpha^\prime NaV_2O_5$ compound. The effective integrals are obtained from valence-spectroscopy {\em ab initio} calculations of embedded crystal fragments (two $VO_5$ pyramids in the different geometries corresponding to the desired parameters). We are using a large configurations interaction (CI) method, where the CI space is specifically optimized to obtain accurate energy differences. We show that the $\alpha^\prime NaV_2O_5$ system can be seen as a two-dimensional asymmetric triangular Heisenberg lattice where the effective sites represent delocalized $V-O-V$ rung entities supporting the magnetic electrons.Comment: 24 pages, 5 figure

First comprehensive contribution to medical ethnobotany of Western Pyrenees

<p>Abstract</p> <p>Background</p> <p>An ethnobotanical and medical study was carried out in the Navarre Pyrenees, an area known both for its high biological diversity and its cultural significance.</p> <p>As well as the compilation of an ethnopharmacological catalogue, a quantitative ethnobotanical comparison has been carried out in relation to the outcomes from other studies about the Pyrenees. A review of all drugs used in the area has also been carried out, through a study of the monographs published by the institutions and organizations responsible for the safety and efficacy of medicinal plants (WHO, ESCOP, and the E Commission of the German Department of Health) in order to ascertain the extent to which the Navarre Pyrenees ethnopharmacology has been officially evaluated.</p> <p>Methods</p> <p>Fieldwork was carried out over two years, from November 2004 to December 2006. During that time we interviewed 88 local people in 40 villages. Information was collected using semi-structured ethnobotanical interviews and the data was analyzed using quantitave indexes: Ethnobotonicity Index, Shannon-Wiener's Diversity, Equitability and The Informant Consensus Factor. The official review has been performed using the official monographs published by the WHO, ESCOP and the E Commission of the German Department of Health.</p> <p>Results</p> <p>The ethnobotanical and medical catalogue of the Navarre Pyrenees Area comprises 92 species, of which 39 have been mentioned by at least three interviewees. The quantitative ethnobotany results show lower values than those found in other studies about the Pyrenees; and 57.6% of the Pyrenees medical ethnobotany described does not figure in documents published by the above mentioned institutions.</p> <p>Conclusion</p> <p>The results show a reduction in the ethnobotanical and medical knowledge in the area of study, when compared to other studies carried out in the Pyrenees. Nevertheless, the use of several species that may be regarded as possible sources for pharmacological studies is reported here such as the bark of <it>Sambucus nigra</it>, the roots of <it>Fragaria vesca</it>, or the leaves of <it>Scrophularia nodosa</it>. These species are not currently approved by the WHO, ESCOP and the E Commission of the German Department of Health, institutions that, apart from encouraging the greater use of plants for medicinal purposes, may help in the design of development plans for these rural areas by validating their traditional medicine.</p

Variation in antiosteoporotic drug prescribing and spending across Spain. A population-based ecological cross-sectional study

Introduction: Evidence has shown that utilization of antiosteoporotic medications does not correspond with risk, and studies on other therapies have shown that adequacy of pharmaceutical prescribing might vary between regions. Nevertheless, very few studies have addressed the variability in osteoporotic drug consumption. We aimed to describe variations in pharmaceutical utilization and spending on osteoporotic drugs between Health Areas (HA) in Spain. Methods: Population-based cross-sectional ecological study of expenditure and utilization of the five therapeutic groups marketed for osteoporosis treatment in Spain in 2009. Small area variation analysis (SAVA) methods were used. The units of analysis were the 168 HA of 13 Spanish regions, including 7.2 million women aged 50 years and older. The main outcomes were the defined daily dose (DDD) per 1000 inhabitants and day (DDD/1000/Day) dispensed according to the pharmaceutical claims reimbursed, and the expenditure on antiosteoporotics at retail price per woman =50 years old and per year. Results: The average osteoporosis drug consumption was 116.8 DDD/1000W/Day, ranging from 78.5 to 158.7 DDD/1000W/Day between the HAs in the 5th and 95th percentiles. Seventy-five percent of the antiosteoporotics consumed was bisphosphonates, followed by raloxifene, strontium ranelate, calcitonins, and parathyroid hormones including teriparatide. Regarding variability by therapeutic groups, biphosphonates showed the lowest variation, while calcitonins and parathyroid hormones showed the highest variation. The annual expenditure on antiosteoporotics was €426.5 million, translating into an expenditure of €59.2 for each woman =50 years old and varying between €38.1 and €83.3 between HAs in the 5th and 95th percentiles. Biphosphonates, despite accounting for 79% of utilization, only represented 63% of total expenditure, while parathyroid hormones with only 1.6% of utilization accounted for 15% of the pharmaceutical spending. Conclusion: This study highlights a marked geographical variation in the prescription of antiosteoporotics, being more pronounced in the case of costly drugs such as parathyroid hormones. The differences in rates of prescribing explained almost all of the variance in drug spending, suggesting that the difference in prescription volume between territories, and not the price of the drugs, is the main source of variation in this setting. Data on geographical variation of prescription can help guide policy proposals for targeting areas with inadequate antiosteoporotic drug use

Medium-range order as an intrinsic property of Co-rich amorphous alloys

X-ray absorption spectroscopy has been used to study the short-range order of some Fe-Co–based amorphous alloys with low Fe concentration prepared by two different methods: melt spinning (FeCoSiB) and electrodeposition (FeCoP). A qualitative analysis of the near-edge region points clearly to the existence of a well-defined chemical affinity of the metalloids Si or P for the Co atoms. A complete EXAFS (Extended X-ray Absorption Fine Structure) analysis establishes that this chemical order induces a strong increase of the topological order in the vicinity of the Fe atoms. This ordered structure involves several coordination shells and is independent of the preparation method and of the nature of the metalloid (Si or P)

Geochemical fingerprinting of Monegros cherts: Redefining the origin of a prehistoric tracer

International audienceThe geographical name of Monegros has traditionally been used to describe a high‐quality, dark‐coloured chert originating in a carbonate lacustrine environment, being one of the most important long‐distance tracers in south‐west Europe during prehistory. This chert type outcrops in the Monegros region, situated in the Ebro Basin (north‐eastern Iberia), but not only there, as cherts with the same descriptions are found in other regions, some far from the homonymous area. Nevertheless, prehistorians working on the characterization of lithic sources have frequently used the term ‘Monegros' to define this chert, basing their attributions solely on macroscopic descriptions. These are not sufficient as they do not allow cherts from the Monegros region to be distinguished from cherts from other regions. In this study, the area where Monegros cherts outcrop was delimited and fieldwork was carried out to identify the origin of the geological formations and the preserved outcrops. The classic approach has proved to be insufficient for this purpose, so geochemical fingerprinting using energy‐dispersive X‐ray fluorescence (ED‐XRF) spectroscopy was performed. The results obtained after this first geochemical approach show that some differences can be found between the different formations in the Monegros region in terms of their major and minor components