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Troncoso R.E.,Chilean Center of Nanosciences and Nanotechnology | Nunez T.S.,University of Chile
Annals of Physics | Year: 2014

We report on the thermal effects on the motion of current-driven massive magnetic skyrmions. The reduced equation for the motion of skyrmion has the form of a stochastic generalized Thiele's equation. We propose an ansatz for the magnetization texture of a non-rigid single skyrmion that depends linearly with the velocity. By using this ansatz it is found that the skyrmion mass tensor is closely related to intrinsic skyrmion parameters, such as Gilbert damping, skyrmion-charge and dissipative force. We have found an exact expression for the average drift velocity as well as the mean-square velocity of the skyrmion. The longitudinal and transverse mobility of skyrmions for small spin-velocity of electrons is also determined and found to be independent of the skyrmion mass. © 2014 Elsevier Inc.


Troncoso R.E.,Chilean Center of Nanosciences and Nanotechnology | Troncoso R.E.,University of Chile | Nunez T.S.,University of Chile
Annals of Physics | Year: 2014

A phenomenological theory is developed, that accounts for the collective dynamics of a Bose-Einstein condensate of magnons. In terms of such description we discuss the nature of spontaneous macroscopic interference between magnon clouds, highlighting the close relation between such effects and the well known Josephson effects. Using those ideas, we present a detailed calculation of the Josephson oscillations between two magnon clouds, spatially separated in a magnonic Josephson junction. © 2014 Elsevier Inc.


Cardenas C.,University of Chile | Cardenas C.,Chilean Center of Nanosciences and Nanotechnology | Ayers P.W.,McMaster University
Physical Chemistry Chemical Physics | Year: 2013

By computing the electron-transfer energies for two million simulated double acid-base exchange reactions, we assess the reliability of the global hard-soft acid-base (HSAB) principle. We find that the HSAB principle is often thwarted by the tendency of strong acids to prefer strong bases. We define the strong-weak and hard-soft driving forces to characterize the strength of these two competing effects, and assess the reliability of the HSAB principle for different strengths and directions of the hard-soft and strong-weak driving forces. We provide a series of probability tables for making informed predictions about the preferred products of double acid-base exchange reactions. © 2013 The Owner Societies.


Troncoso R.E.,University of Chile | Troncoso R.E.,Chilean Center of Nanosciences and Nanotechnology | Nunez A.S.,University of Chile
Physical Review B - Condensed Matter and Materials Physics | Year: 2014

We study the behavior of skyrmions in thin films under the action of stochastic torques arising from thermal fluctuations. We find that the Brownian motion of skyrmions is described by a stochastic Thiele's equation and its corresponding Fokker-Planck equation. The resulting Fokker-Planck equation is recognized as the one for a high-friction Brownian particle which has been studied extensively in different physical contexts. It is shown that thermal fluctuations favor the skyrmion motion allowing a finite mobility even in presence of pinning traps. We calculate explicitly the mobility tensor of skyrmions in linear response to an electric current finding that it increases with temperature. © 2014 American Physical Society.


Guarda A.,Chilean Center of Nanosciences and Nanotechnology | Rubilar J.F.,Chilean Center of Nanosciences and Nanotechnology | Miltz J.,Technion - Israel Institute of Technology | Galotto M.J.,Chilean Center of Nanosciences and Nanotechnology
International Journal of Food Microbiology | Year: 2011

The aim of the present study was to determine the antimicrobial (AM) properties of plastic flexible films with a coating of microcapsules containing carvacrol and thymol as natural AM agents. Microencapsulation of these agents enables their controlled release and leads to the destruction (or growth inhibition) of a broad spectrum of microorganisms such as, Escherichia coli O157:H7, Staphylococcus aureus, Listeria innocua, Saccharomyces cerevisiae and Aspergillus niger. It was found that the studied AM agents are strong inhibitors to the growth of mycelium, but they were not effective against spore germination of mold. Thymol (T) and carvacrol (C) showed a significant AM activity against the studied microorganisms, with minimal inhibitory concentrations (MIC) of 125-250. ppm and 75-375. ppm for thymol and carvacrol respectively. The synergistic effect of combinations of thymol and carvacrol was also studied and it was found that the highest synergism was achieved at a concentration of 50% T and 50% C. The release of the AM agents was carried out at 4 °C during 28. days. The concentration of the microencapsulated AM agents showed a range of zones of inhibition of 4.3-11.3. mm for the microorganisms at 10% of thymol and 10% of carvacrol. At these concentrations the release of the AM agents (within 48. h) was greater than required for the most resistant microorganism (E .coli O157:H7), as reflected by the relatively large zone of inhibition. The results of the present study confirm the suitability of using microencapsulated thymol and carvacrol incorporated in polymer films for AM food packaging. © 2011 Elsevier B.V.

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