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SEMINARIO DFI: Tayloring CO2 Adsorption on Perovskite- Ferroelectric Oxides Imprimir


Alejandro L. Cabrera

Instituto de Fisica, PUC


Viernes 31 de mayo, 16:00 h

Av. Blanco Encalada 2008, 3er piso

Sala de Seminarios


Our long standing pursue of the effect of a substrate's ferroelectric state on a chemical reaction taking place on its surface is finally becoming an accepted fact by the scientific community. Our research’s group at  Pontificia Universidad Catolica have published about 5 articles dealing with the effect of the ferroelectric transition in BaTiO3, LiNbO3 and KNbO3 on the adsorption of carbon dioxide, being the work on the KNbO3  the more conclusive demonstration of the effect [1]. Recent results on this subject have been published by other groups [2,3]. Our more recent publications on the subject deals with the manipulation of the ferroelectric domains in 4% Nb 20/80 Pb(Zr,Ti)O3 thin films using an electric field and the effect on the CO2 adsorption.  The adsorption experiments and the characterization of the ferroelectric materials will be discussed in this presentation.



[1] "Desorption of carbon dioxide from small potassium niobate particles induced by the particles’ ferroelectric transition" E. Ramos-Moore, J.A. Baier-Saip and A.L. Cabrera, Surface Science, Vol. 600, (2006)  3472-3476.

[2] “Effect of the ferroelectric poling on the adsorption of 2-propanol on LiNbO3(0001)” by Y. Yun, L. Kampshulte, M. Li, D. Liao and E. I. Altman, J. Phys. Chem. C (2007), 111, 13951.

[2]."Effect of Ferroelectric polarization on the adsorption reaction of ethanol on BaTiO3" by M.H. Zhao, D. A. Bonnell and J. M. Vohs, Surf. Sci.602 (2008) 2849.



Seminarios Anteriores

SEMINARIO DFI: Metabolic entanglement and biological complexity Imprimir

Expositor: Juan Keymer

Viernes 24 de mayo, 16 h

Av Blanco Encalada 2008, 3er piso

Sala de seminarios



Conceptually, I will be talking about the basic notion of what is a population from the perspective of functional niche coherence among individuals (as suppose to being just a number density). Experimentally, I will show and discuss data of the colonization of a patchy ecosystem by two neutrally labeled, but otherwise isogenic, strains of Escherichia coli. One-dimensional arrays of habitat patches linked by connectors were inoculated at opposite ends by two fluorescently-labeled strains and studied by time-lapse microscopy. The habitats are colonized by a series of traveling waves followed by an expansion front. When colonization waves collide, they branch into a reflected wave, a stationary population, and a wave continuing in the same direction. Subsequent expansion fronts coming from opposite sides remain largely segregated in space and often one will displace the other from most of the habitat. Although all cultures are started from the same -80°C frozen stock, spatiotemporal colonization patterns in habitat replicas inoculated with cells from the same ancestral culture are significantly more similar to each other than to patterns in identical habitats inoculated with cells from different ancestral cultures. Cells coming from different ancestral monocultures do not mix in the habitat, while cells coming from a mixed ancestral co-culture colonize the habitat together and do not separate spatially. Using physically separated, but chemically coupled habitats we show that colonization waves and expansion fronts interact mostly through chemical fields. Together, our data show the crucial roles of inoculum ancestry and chemical coupling between cells in determining the outcome of habitat colonization. 

SEMINARIO DFI: Dinámica de la Magnetización en multicapas Ferromagnético/Metal Imprimir


Roberto Rodríguez

Facultad de Física, PUC


Viernes 17 de mayo, 16:00 h

Av. Blanco Encalada 2008, 3er piso

sala de seminarios


Una de las propiedades fundamentales de un sistema magnético es la manera en la que su magnetización se relaja hacia el equilibrio. Este proceso, gobernado por las interacciones entre los espines y la estructura del sistema magnético es importante desde el punto de vista de física básica y por las aplicaciones tecnológicas. Por varias décadas la relajación de la magnetización ha sido investigada experimentalmente en el bulk y en capas finas principalmente a través de la medición del ancho de línea en resonancia ferromagnética (FMR) en frecuencias de microondas. En capas finas magnéticas y multicapas nuevos mecanismos de relajación han sido descubiertos en la última década siendo los más importantes los mecanismos de dispersión de dos magnons [1, 2] debido a defectos en las superficies e intracapas y el mecanismo de bombeamiento de espines [3]. Estos procesos contribuyen con una taza de relajación adicional que aumenta con la disminución de la espesura de la capa magnética dominando en capas finas. En este seminario revisamos los mecanismos de relajación de la magnetización en capas y multicapas finas magnéticas ferromagnético/ metal no magnético y analizamos la generación de corrientes puras de spin en estas estructuras.


[1] R. Arias, D. L. Mills, Phys. Rev. B 60, 7395 (1999).

[2] P. Landeros, R. E. Arias, and D. L. Mills, Phys. Rev. B 77, 214405 (2008).

[3] Y. Tserkovnyak, A. Brataas, G. E. Bauer and B. I. Halperin, Rev. Mod. Phys. 77, 1375 (2005).


SEMINARIO DFI: Landau-Zener transitions, interferometry and more in a PT-symmetric Imprimir


Luis Morales

Facultad de Física



Viernes 10 de mayo, 16:00 h

Av Blanco Encalada 2008, 3er piso

Sala de seminarios



PT symmetric optical systems exhibit novel properties such as

non-reciprocal light propagation and tailored energy flow. The complex

refractive index of these systems can be manipulated in order to control

the losses and gain of a propagating light beam. In particular, by using

an optical waveguide array with a constant electric field, simple control

of the gain and losses is achieved. In this talk the navigation through

the energy spectrum for a PT symmetric periodic lattice in the presence of

an external force is analyzed.  For a constant force and within a two mode

approximation, exact analytical results for the occupation probability of

the bands are derived. As a result of the Landau-Zener interband

transitions interesting effects for the light propagation are revealed

with the help of numerical simulations.


The analysis is extended to the presence of an AC force where

interferometry between states of the bands is demonstrated. In this new

scenario the phase accumulated after every transition is shown to lead to

a constructive or destructive interference which maximizes the gain and



Finally, future research lines are pointed out.

SEMINARIO DFI: Redes de Homeostasis Proteica y su rol en enfermedades neurodegenerativas. Imprimir



Claudio Hetz

Instituto de Neurociencia Biomédica, Facultad de medicina, Universidad de Chile


Viernes 3 de mayo, 16:00 h

Av Blanco Encalada 2008, 3er piso

Sala de seminarios



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