Magnetoelectric Devices for Spintronics Fusil, S; Garcia, V; Barthélémy, A ...
Annual review of materials research,
07/2014, Letnik:
44, Številka:
1
Journal Article
Recenzirano
The control of magnetism by electric fields is an important goal for the future development of low-power spintronics. Various approaches have been proposed on the basis of either single-phase ...multiferroic materials or hybrid structures in which a ferromagnet is influenced by the electric field applied to an adjacent insulator (usually having a ferroelectric, piezoelectric, or multiferroic character). The electric field effect on magnetism can be driven by purely electronic or electrostatic effects or can occur through strain coupling. Here we review progress in the electrical control of magnetic properties (anisotropy, spin order, ordering temperature, domain structure) and its application to prototype spintronic devices (spin valves, magnetic tunnel junctions). We tentatively identify the main outstanding difficulties and give perspectives for spintronics and other fields.
Tropical plant species are expected to have high heat tolerance reflecting phenotypic adjustments to warm regions or their evolutionary adaptation history. However, tropical highland specialists ...adapted to the colder temperatures found in the highlands, where short and prostrated vegetation decouples plants from ambient conditions, could exhibit different upper thermal limits than those of their lowland counterparts. Here we evaluated leaf heat tolerance of 21 tropical alpine paramo species to determine: 1) whether species with restricted distribution (i.e., highland specialists) have lower heat tolerance and are more vulnerable to warming than species with widespread distribution; 2) whether different growth forms have different heat tolerance; and 3) whether species height (i.e., microhabitat) influences its heat tolerance. We quantified heat tolerance by evaluating T50, which is the temperature that causes a reduction in 50% of initial Fv/Fm values and reflects an irreversible damage to the photosynthetic apparatus. Additionally, we estimated the thermal safety margins as the difference between T50 and the maximum leaf temperature registered for the species. All species presented high T50 values ranging between 45.4°C and 53.9°C, similar to those found for tropical lowland species. Heat tolerance was not correlated with species distributions or plant height, but showed a strong relationship with growth form, with rosettes having the highest heat tolerance. Thermal safety margins ranged from 12.1 to 31.0°C. High heat tolerance and broad thermal safety margins suggest low vulnerability of paramo species to warming as long as plants are capable of regulating the leaf temperature within this threshold. Whether paramo plants would be able to regulate leaf temperature if drought episodes become more frequent and transpirational cooling is compromised is the next question that needs to be answered.
Although ferromagnets have many applications, their large magnetization and the resulting energy cost for switching magnetic moments bring into question their suitability for reliable low-power ...spintronic devices. Non-collinear antiferromagnetic systems do not suffer from this problem, and often have extra functionalities: non-collinear spin order may break space-inversion symmetry and thus allow electric-field control of magnetism, or may produce emergent spin-orbit effects that enable efficient spin-charge interconversion. To harness these traits for next-generation spintronics, the nanoscale control and imaging capabilities that are now routine for ferromagnets must be developed for antiferromagnetic systems. Here, using a non-invasive, scanning single-spin magnetometer based on a nitrogen-vacancy defect in diamond, we demonstrate real-space visualization of non-collinear antiferromagnetic order in a magnetic thin film at room temperature. We image the spin cycloid of a multiferroic bismuth ferrite (BiFeO
) thin film and extract a period of about 70 nanometres, consistent with values determined by macroscopic diffraction. In addition, we take advantage of the magnetoelectric coupling present in BiFeO
to manipulate the cycloid propagation direction by an electric field. Besides highlighting the potential of nitrogen-vacancy magnetometry for imaging complex antiferromagnetic orders at the nanoscale, these results demonstrate how BiFeO
can be used in the design of reconfigurable nanoscale spin textures.
We characterize the good weights for a certain weighted weak-type iterated Hardy inequality to hold. As a consequence, we get the characterizations of some weighted weak-type bilinear Hardy ...inequalities.
A novel methodology for printing 3D objects with spatially resolved mechanical and chemical properties is reported. Photochromic molecules are used to control polymerization through coherent ...bleaching fronts, providing large depths of cure and rapid build rates without the need for moving parts. The coupling of these photoswitches with resin mixtures containing orthogonal photo‐crosslinking systems allows simultaneous and selective curing of multiple networks, providing access to 3D objects with chemically and mechanically distinct domains. The power of this approach is showcased through the one‐step fabrication of bioinspired soft joints and mechanically reinforced “brick‐and‐mortar” structures.
One‐step multimaterial 3D printing with visible light for the production of bioinspired composites is presented. The technique, solution mask liquid lithography, is enabled by photochromic molecules that bleach upon exposure to light and, in combination with orthogonal photosensitizers, allowing the production of multimaterial parts with intricate motifs such as soft joints and brick‐and‐mortar structures.
The identification of tumour biomarkers that detect the presence of disease using noninvasive diagnostic procedures is a key part of cancer research. We determined in plasma the vesicle-related ...microRNA (miRNA) expression profile of nonsmall cell lung cancer (NSCLC) and evaluate whether plasma miRNAs can be both discriminating (between patients and healthy controls) and prognostic markers. 365 human miRNAs were analysed by Taqman® low-density arrays (Applied Biosystems, Foster City, CA, USA) in the plasma from 28 NSCLC patients and 20 controls. Five selected miRNAs (let-7f, miR-20b, miR-30e-3p, miR-223 and miR-301) were validated independently by real-time PCR in plasma from 78 NSCLC and 48 controls and correlated with pathologic parameters and survival. Levels of let-7f, miR-20b and miR-30e-3p were decreased in plasma vesicles of NSCLC patients. Moreover, levels of let-7f and miR-30e-3p distinguished between two groups of patients for stage of disease and therefore possibility of surgery. Plasma levels of miR-30e-3p and let-7f were associated with short disease-free survival and overall survival, respectively. NSCLC patients and healthy controls differ in vesicle-related miRNAs in plasma. Levels of let-7f and miR-30e-3p in NSCLC patients are associated with poor outcome. Thus, plasma vesicle-related miRNAs obtained by noninvasive methods could serve as circulating tumour biomarkers of discriminating and prognostic value.
Abstract
Antiferromagnetic thin films are currently generating considerable excitement for low dissipation magnonics and spintronics. However, while tuneable antiferromagnetic textures form the ...backbone of functional devices, they are virtually unknown at the submicron scale. Here we image a wide variety of antiferromagnetic spin textures in multiferroic BiFeO
3
thin films that can be tuned by strain and manipulated by electric fields through room-temperature magnetoelectric coupling. Using piezoresponse force microscopy and scanning NV magnetometry in self-organized ferroelectric patterns of BiFeO
3
, we reveal how strain stabilizes different types of non-collinear antiferromagnetic states (bulk-like and exotic spin cycloids) as well as collinear antiferromagnetic textures. Beyond these local-scale observations, resonant elastic X-ray scattering confirms the existence of both types of spin cycloids. Finally, we show that electric-field control of the ferroelectric landscape induces transitions either between collinear and non-collinear states or between different cycloids, offering perspectives for the design of reconfigurable antiferromagnetic spin textures on demand.
Defective textures in dry-cured ham are a common problem that causes important economic losses in the ham industry. An increase of proteolysis during the dry-cured ham processing may lead to high ...adhesiveness and consumer rejection of the product. Therefore, the influence of proteolysis index (PI) on instrumental adhesiveness, free amino acids and volatile profile of dry-cured ham was assessed. Two hundred Spanish dry-cured ham units were firstly classified according to their PI: low PI (<32%), medium PI (32–36%) and high PI (>36%). Instrumental adhesiveness was affected by PI, showing the lowest values in the batch with low PI. Significant differences (P < 0.05) among groups were found in six amino acids: serine, taurine, cysteine, methionine, isoleucine and leucine. The content of leucine, serine, methionine, and isoleucine significantly (P < 0.05) increased as the proteolysis index rose. However, taurine and cysteine content showed an opposite behaviour, reaching the highest values in the dry-cured hams with low PI.
Significant differences (P < 0.001) in the total content of volatile compounds among ham groups were observed, with the highest concentration in the batch with low PI, and decreasing the concentration as the PI increased. Regarding the different chemical families of volatiles, the hydrocarbons (the main family), alcohols, aldehydes, ketones and acids were more abundant in the hams showing the lowest PI. Esters did not show significant differences among the three batches of hams studied. The present study demonstrated that, apart from the effect on the adhesiveness, an excessive proteolysis seems to be associated with negative effects on the taste and aroma of the dry-cured ham.
Display omitted
•An excessive proteolysis influenced negatively the aroma of dry-cured hams.•The total free amino acid content was not affected by the proteolysis index (PI).•The content of leucine, serine, methionine, and isoleucine significantly increased as the PI rose.•The highest concentration of volatile compounds were observed in hams with low PI.
Controlling magnetism by means of electric fields is a key issue for the future development of low-power spintronics. Progress has been made in the electrical control of magnetic anisotropy, domain ...structure, spin polarization or critical temperatures. However, the ability to turn on and off robust ferromagnetism at room temperature and above has remained elusive. Here we use ferroelectricity in BaTiO3 crystals to tune the sharp metamagnetic transition temperature of epitaxially grown FeRh films and electrically drive a transition between antiferromagnetic and ferromagnetic order with only a few volts, just above room temperature. The detailed analysis of the data in the light of first-principles calculations indicate that the phenomenon is mediated by both strain and field effects from the BaTiO3. Our results correspond to a magnetoelectric coupling larger than previous reports by at least one order of magnitude and open new perspectives for the use of ferroelectrics in magnetic storage and spintronics.
PDF
