87 research outputs found
Oxygen doping and polaron magnetic coupling in Alq films
The understanding of the Physics underlying the performances of organic
spin-valve devices is still incomplete. According to some recent models, spin
transport takes place in an impurity band inside the fundamental gap of organic
semiconductors. This seems to be confirmed by recent experiments performed with
LaSrMnO/Alq/AlO/Co devices. The reported results
suggest a possible correlation between the magnetoresistance and the variable
oxygen doping in the Alq spacer. In this paper we investigate by means of
first-principles calculations the electronic and magnetic properties of O
molecules and ions in Alq films to establish whether oxygen plays any
important role for spin transport in
LaSrMnO/Alq/AlO/Co devices. The conclusion is that
it does not. In fact, we show that O molecules do not form an impurity band
and there is no magnetic interaction between them. In contrast, we suggest that
spin-transport may be enabled by the direct exchange coupling between Alq
ions.Comment: 6 pages, 2 figure
Electron doping and magnetic moment formation in N- and C-doped MgO
The formation of the magnetic moment in C- and N-doped MgO is the result of a
delicate interplay between Hund's coupling, hybridization and Jahn-Teller
distortion. The balance depends on a number of environmental variables
including electron doping. We investigate such a dependence by self-interaction
corrected density functional theory and we find that the moment formation is
robust with respect to electron doping. In contrast, the local symmetry around
the dopant is more fragile and two different geometries can be stabilized.
Crucially the magnetic moment is always extremely localized, making any carrier
mediated picture of magnetism in d^0 magnets unlikely
Current-induced spin polarization at metallic surfaces from first-principles
We present the results of first-principles calculations based on density
functional theory estimating the magnitude of the current-induced spin
polarization (CISP) at the surfaces of the transition metals with fcc and
bcc crystal structures. We predict that the largest surface CISP occurs for W
and Ta, whereas CISP is considerably weaker for Pt and Au surfaces. We then
discuss how CISP emerges over a length scale equal to few atomic layers as
opposed to the spin accumulation characteristic of the SHE, which is related to
the materials' spin diffusion length. Finally, using our estimates for the CISP
magnitude, we suggest that the spin density appearing near W surfaces in
experiments is mostly due to CISP, whereas that at Pt surfaces stems from the
Hall effect
Transmission through correlated CunCoCun heterostructures
Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).-- et al.We propose a method to compute the transmission through correlated heterostructures by combining density functional and many-body dynamical mean field theories. The heart of this combination consists in porting the many-body self-energy from an all electron basis into a pseudopotential localized atomic basis set. Using this combination we study the effects of local electronic interactions and finite temperatures on the transmission across the Cu4CoCu4 metallic heterostructure. It is shown that as the electronic correlations are taken into account via a local but dynamic self-energy, the total transmission at the Fermi level gets reduced (predominantly in the minority-spin channel), whereby the spin polarization of the transmission increases. The latter is due to a more significant d-electron contribution, as compared to the noncorrelated case in which the transport is dominated by s and p electrons.Financial support offered by the Augsburg Center for Innovative Technologies and by the Deutsche Forschungsgemeinschaft (through TRR 80) is gratefully acknowledged.
A.D. and I.R. acknowledge financial support from the European Union through the EU FP7 program through project 618082 ACMOL. M.R. also acknowledges support by the Ministry of Education, Science, and Technological Development of the Republic of Serbia under Projects No. ON171017 and No. III45018. A.O. would like to acknowledge financial support from the Axel Hultgren foundation and the Swedish steel producer’s association (Jernkontoret). L.V. acknowledges support from the Swedish Research Council.Peer Reviewe
ERAS in General Thoracic Surgery
Enhanced recovery after surgery (ERAS®) is a strategy that seeks to reduce patients’ perioperative stress response, thereby reducing potential complications, decreasing hospital length of stay and enabling patients to return more quickly to their baseline functional status. This programme results from the union of several perioperative clinical elements that have individually proved to be beneficial to the patient and have showed, when used together, a synergy that results in a significant outcome improvement. The term was coined at the end of the 1990s and originally used to refer to a complex fast-track programme in open colorectal surgery. Subsequently, the practice has spread to other surgical specialties centralising the interest of clinicians and researchers. The objective of this chapter is to analyse the key elements of an ERAS protocol applicable to minimally invasive thoracic surgery
A theoretical perspective on the modification of the magnetocrystalline anisotropy at molecule-cobalt interfaces
We study the modification of the magnetocrystalline anisotropy (MCA) of Co
slabs induced by several different conjugated molecular overlayers, i.e.,
benzene, cyclooctatetraene, naphthalene, pyrene and coronene. We perform
first-principles calculations based on Density Functional Theory and the
magnetic force theorem. Our results indicate that molecular adsorption tends to
favour a perpendicular MCA at surfaces. A detailed analysis of various
atom-resolved quantities, accompanied by an elementary model, demonstrates that
the underlying physical mechanism is related to the metal-molecule interfacial
hybridization and, in particular, to the chemical bonding between the molecular
C and the out-of-plane Co orbitals. This effect can be
estimated from the orbital magnetic moment of the surface Co atoms, a
microscopic observable accessible to both theory and experiments. As such, we
suggest a way to directly assess the MCA modifications at molecule-decorated
surfaces, overcoming the limitations of experimental studies that rely on fits
of magnetization hysteresis loops. Finally, we also study the interface between
Co and both C and Alq, two molecules that find widespread use in
organic spintronics. We show that the modification of the surface Co MCA is
similar upon adsorption of these two molecules, thereby confirming the results
of recent experiments.Comment: 10 figures in main text and 3 in the SM, 20 page
Non-locally sensing the magnetic states of nanoscale antiferromagnets with an atomic spin sensor
The ability to sense the magnetic state of individual magnetic nano-objects
is a key capability for powerful applications ranging from readout of
ultra-dense magnetic memory to the measurement of spins in complex structures
with nanometer precision. Magnetic nano-objects require extremely sensitive
sensors and detection methods. Here we create an atomic spin sensor consisting
of three Fe atoms and show that it can detect nanoscale antiferromagnets
through minute surface-mediated magnetic interaction. Coupling, even to an
object with no net spin and having vanishing dipolar stray field, modifies the
transition matrix element between two spin states of the Fe-atom-based spin
sensor that changes the sensor's spin relaxation time. The sensor can detect
nanoscale antiferromagnets at up to three nanometers distance and achieves an
energy resolution of 10 micro-electronvolts surpassing the thermal limit of
conventional scanning probe spectroscopy. This scheme permits simultaneous
sensing of multiple antiferromagnets with a single spin sensor integrated onto
the surface.Comment: 30 pages main text, 6 figures, Supplementary materials not inculde
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