Impurity induced enhancement of perpendicular magnetic anisotropy in Fe/MgO tunnel junctions

Using first-principles calculations, we investigated the impact of chromium (Cr) and vanadium (V) impurities on the magnetic anisotropy and spin polarization in Fe/MgO magnetic tunnel junctions. It is demonstrated using layer resolved anisotropy calculation technique, that while the impurity near the interface has a drastic effect in decreasing the perpendicular magnetic anisotropy (PMA), its position within the bulk allows maintaining high surface PMA. Moreover, the effective magnetic anisotropy has a strong tendency to go from in-plane to out-of-plane character as a function of Cr and V concentration favoring out-of-plane magnetization direction for ~1.5 nm thick Fe layers at impurity concentrations above 20 %. At the same time, spin polarization is not affected and even enhanced in most situations favoring an increase of tunnel magnetoresistance (TMR) values.Comment: 6 pages, 3 figure

Anatomy of perpendicular magnetic anisotropy in Fe/MgO magnetic tunnel junctions: First principles insight

Using first-principles calculations, we elucidate microscopic mechanisms of perpendicular magnetic anisotropy (PMA)in Fe/MgO magnetic tunnel junctions through evaluation of orbital and layer resolved contributions into the total anisotropy value. It is demonstrated that the origin of the large PMA values is far beyond simply considering the hybridization between Fe-3d$and O-2p orbitals at the interface between the metal and the insulator. On-site projected analysis show that the anisotropy energy is not localized at the interface but it rather propagates into the bulk showing an attenuating oscillatory behavior which depends on orbital character of contributing states and interfacial conditions. Furthermore, it is found in most situations that states with$d_{yz(xz)}$and$d_{z^2}$character tend always to maintain the PMA while those with$d_{xy}$and$d_{x^2-y^2}$character tend to favor the in-plane anisotropy. It is also found that while MgO thickness has no influence on PMA, the calculated perpendicular magnetic anisotropy oscillates as a function of Fe thickness with a period of 2ML and reaches a maximum value of 3.6 mJ/m$^2$.Comment: 5 pages, 5 figure

Magnetic Insulator-Induced Proximity Effects in Graphene: Spin Filtering and Exchange Splitting Gaps

We report on first-principles calculations of spin-dependent properties in graphene induced by its interaction with a nearby magnetic insulator (Europium oxide, EuO). The magnetic proximity effect results in spin polarization of graphene $\pi$ orbitals by up to 24 %, together with large exchange splitting bandgap of about 36 meV. The position of the Dirac cone is further shown to depend strongly on the graphene-EuO interlayer. These findings point towards the possible engineering of spin gating by proximity effect at relatively high temperature, which stands as a hallmark for future all-spin information processing technologies.Comment: 5 pages, 4 figure

Nasogastric Tube Feeding-Induced Esophageal Bezoar: Case Description

Background. Bezoars are well established entities causing gastrointestinal obstructions. Depending on the prominent constituent of these bezoars, the latter are divided into four subtypes: pharmacobezoars, lactobezoars, trichobezoars, and phytobezoars. Less frequently reported types of bezoars are reported including those formed secondary to nasogastric tube feeding with casein-based formulas. Case Presentation. A 69-year-old male presented following cardiac arrest postmyocardial infarction. Patient sustained anoxic brain injury after resuscitation, rendering him ventilator dependant along with nasogastric tube feeding, initially. Dislodging of the nasogastric tube at one time rendered it difficult to reinsert it, with investigation showing the presence of calcified material within the distal oesophagus, mainly composed of casein-based products secondary to enteral feeding. Conclusion. Bezoars are well known to cause gastrointestinal obstructions due to their indigestible characteristics within the alimentary tract. More rare causes of bezoars include those formed from casein-based feeding formulas administered to patients with sustained enteral feeding. Esophageal obstruction, secondary to casein-based bezoars, occurs due to multiple risk factors, especially in those necessitating intensive care. Approach in such scenarios requires a multiteam approach

House of Physical Activity Cards: the Lancet Observatory experience

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‘The phoenix that always rises from the ashes’: an exploratory qualitative study of the experiences of an initiative informed by principles of psychological first aid following the Beirut blast

BACKGROUND: On 4 August 2020, an explosion occurred in Beirut, Lebanon. Hundreds of people were killed, thousands injured and displaced. An initiative was rapidly initiated to provide remote support informed by psychological first aid for the mental health of Lebanese young adults affected by the blast. However, little is known about recipients’ experiences of such initiatives. OBJECTIVES: This study aimed to qualitatively explore the experiences of supporters and recipients in the community-led initiative following the blast. METHOD: We recruited a diverse sample of four supporters and four Lebanese recipients who took part in the Beirut initiative. Semi-structured interviews were conducted with participants. Reflexive thematic analysis was used to analyse the qualitative data. RESULTS: We developed five themes from the qualitative interviews, which highlighted ideas around accessibility, alienation, the relationship, elements of the safe space created by the initiative, and unmet needs and areas for improvement. Recipients described the detrimental impact of the blast on their mental health within the Lebanese context and beyond. Recipients and supporters elucidated complex experiences of the support and its impact. CONCLUSIONS: Our findings suggest remote support has the potential to be acceptable for young adults in Lebanon. Further research into support informed by psychological first aid after similar crisis events is warranted