26 research outputs found
Dynamic Origin of Vortex Core Switching in Soft Magnetic Nanodots
The magnetic vortex with the in-plane curling magnetization and the
out-of-plane magnetization at the core is a unique ground state in nanoscale
magnetic elements. This kind of magnetic vortex can be used as a memory unit
for information storage, through its downward or upward core-orientation and,
thus, controllable core switching deserves some special attention. Our
analytical and micromagnetic calculations reveal that the origin of the vortex
core reversal is a gyrotropic field. This field is induced by vortex dynamic
motion and is proportional to the velocity of the moving vortex. Our
calculations elucidate the physical origin of the vortex core dynamic reversal
and offer a key to effective manipulation of the vortex-core orientation.Comment: 17 pages and 3 figure
Dynamic origin of azimuthal modes splitting in vortex-state magnetic dots
A spin wave theory explaining experimentally observed frequency splitting of
dynamical excitations with azimuthal symmetry of a magnetic dot in a vortex
ground state is developed. It is shown that this splitting is a result of the
dipolar hybridization of three spin wave modes of a dot having azimuthal
indices |m|=1: two high-frequency azimuthal excitation modes of the in-plane
part of the vortex with indices m = +/-1 and a low-frequency m= +1 gyrotropic
mode describing the translational motion of the vortex core. The analytically
calculated magnitude of the frequency splitting is proportional to the ratio of
the dot thickness to its radius and quantitatively agrees with the results of
time resolved Kerr experiments.Comment: 10 pages, 5 figure
Real-time observation of the dry oxidation of the Si(100) surface with ambient pressure x-ray photoelectron spectroscopy
We have applied ambient-pressure x-ray photoelectron spectroscopy with Si 2p chemical shifts to study the real-time dry oxidation of Si(100), using pressures in the range of 0.01-1 Torr and temperatures of 300-530 ??C, and examining the oxide thickness range from 0 to ???25 A. The oxidation rate is initially very high (with rates of up to ???225 Ah) and then, after a certain initial thickness of the oxide in the range of 6-22 A is formed, decreases to a slow state (with rates of ???1.5-4.0 Ah). Neither the rapid nor the slow regime is explained by the standard Deal-Grove model for Si oxidation.open171
Vortex dynamics in confined stratified conditions
We report on linear spin dynamics in the vortex state of the Permalloy dots
subjected to stratified (magnetic) field. We demonstrate experimentally and by
simulations the existence of two distinct dynamic regimes corresponding to the
vortex stable and metastable states. Breaking cylindrical symmetry leads to
unexpected eigenmodes frequency splitting in the stable state and appearance of
new eigenmodes in the metastable state above the vortex nucleation field.
Dynamic response in the metastable state strongly depends on relative
orientation of the external rf pumping and the bias magnetic fields. These
findings may be relevant for different vortex states in confined and stratified
conditions
In situ observation of wet oxidation kinetics on Si(100) via ambient pressure x-ray photoemission spectroscopy
e initial stages of wet thermal oxidation of Si (100) - (2??1) have been investigated by in situ ambient pressure x-ray photoemission spectroscopy, including chemical-state resolution via Si 2p core-level spectra. Real-time growth rates of silicon dioxide have been monitored at 100 mTorr of water vapor. This pressure is considerably higher than in any prior study using x-ray photoemission spectroscopy. Substrate temperatures have been varied between 250 and 500 ??C. Above a temperature of ???400 ??C, two distinct regimes, a rapid and a quasisaturated one, are identified, and growth rates show a strong temperature dependence which cannot be explained by the conventional Deal-Grove model.open7
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In-Situ observation of wet oxidation kinetics on Si (100) via ambient pressure x-ray photoemission spectroscopy
The initial stages of wet thermal oxidation of Si(100)-(2x1) have been investigated by in-situ ambient pressure x-ray photoemission spectroscopy (APXPS), including chemical-state resolution via Si 2p core-level spectra. Real-time growth rates of silicon dioxide have been monitored at 100 mTorr of water vapor. This pressure is considerably higher than in any prior study using XPS. Substrate temperatures have been varied between 250 and 500 C. Above a temperature of {approx} 400 C, two distinct regimes, a rapid and a quasi-saturated one, are identified and growth rates show a strong temperature dependence which cannot be explained by the conventional Deal-Grove model
Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches
Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly
Extracellular vesicles for tissue repair and regeneration: evidence, challenges and opportunities
Extracellular vesicles (EVs) are biological nanoparticles naturally secreted by cells, acting as delivery vehicles for molecular messages. During the last decade, EVs have been assigned multiple functions that have established their potential as therapeutic mediators for a variety of diseases and conditions. In this review paper, we report on the potential of EVs in tissue repair and regeneration. The regenerative properties that have been associated with EVs are explored, detailing the molecular cargo they carry that is capable of mediating such effects, the signaling cascades triggered in target cells and the functional outcome achieved. EV interactions and biodistribution in vivo that influence their regenerative effects are also described, particularly upon administration in combination with biomaterials. Finally, we review the progress that has been made for the successful implementation of EV regenerative therapies in a clinical setting