PhD and Postdoc opportunities in the physics of disordered systems in Bariloche (Argentina)

a call is now open for national PhD and postdoc fellowships in Argentina
https://convocatorias.conicet.gov.ar/becas/
Fellowships are scheduled to begin on April 1st 2021.

We invite candidates who are interested in applying to work in the physics of Driven Disordered Systems at the Condensed Matter Theory Group in Bariloche Atomic Centre to contact us.
Please, send a CV and a brief motivation statement before July 6th to
ferrero@cab.cnea.gov.ar

Details (in Spanish) follow:

Tema: Fenómenos críticos, memoria, localización, avalanchas y precursores de eventos catastróficos en la deformación plástica de sólidos amorfos

Tipo de trabajo: Modelado teórico-computacional de sistemas desordenados forzados. Simulaciones de modelos elasto-plásticos de sólidos amorfos y dinámica molecular de vidrios.

Director: Ezequiel Ferrero

Lugar de Trabajo:
Grupo de Teoría de la Materia Condensada – Centro Atómico Bariloche

Fecha límite de contacto 6/7/20: ferrero@cab.cnea.gov.ar

Descripción:
Bajo la aplicación de una tensión, por ejemplo un estrés de cizalla, los sólidos amorfos se deforman elásticamente, como un sólido cristalino, si la tensión es pequeña; pero cuando el estrés aplicado supera un umbral crı́tico el material cede y fluye, como un lı́quido viscoso. Este es el fenómeno de “fluencia” o yielding. Para los materiales frágiles (e.g. vidrios de sı́lice), este proceso culmina rápidamente en la fractura; pero un amplio espectro de materiales (espumas, emulsiones, vidrios coloidales, vidrios metálicos, medios granulares) sobrevienen una transición a un estado en donde el material simplemente deja de resistir y fluye. La transición dinámica entre un estado sólido de respuesta elástica y un estado de flujo plástico se conoce como la transición de yielding. Asociados a esta transición de fase dinámica encontramos fenómenos crı́ticos, analogı́as con otras transiciones de fase (de equilibrio o forzadas). En particular, se observan avalanchas de eventos plásticos, efectos de memoria y localización ante cizalla oscilante y comportamientos de relajación que se constituyen en efectos precursores de la fractura. En esta fı́sica compleja y rica de los materiales amorfos bajo deformación se basa el presente proyecto.

Posibles líneas de trabajo:
– Estudio de cizalla oscilante: Efectos de memoria, avalanchas y bandas de cizalla en vidrios
– Efectos precursores de fractura: Fenómenos de “creep” (térmico y atérmico) en materia blanda
– Caracterización del ruido mecánico y la estabilidad marginal en yielding

PhD and Postdoc opportunities in the physics of disordered systems in Bariloche (Argentina)

the call is open for national PhD and postdoc fellowships in Argentina
https://convocatorias.conicet.gov.ar/becas/
A number of fellowships is specially saved for Latin American applicants.

I invite candidates who are interested in applying to work on the physics of Driven Disordered Elastic Systems or the Plastic Deformation of Amorphous Solids at the Condensed Matter Theory Group in Centro Atómico Bariloche to contact me sending a CV a brief motivation statement to hello@ezequielferrero.com, as soon as possible.

For more information, please do not hesitate to contact me.

Only a few days left before the start of Yielding2019

Our Satellite workshop about the yielding phenomena in disordered systems is about to start in a few days in Bariloche, Argentina.
We’re very excited about so many first class scientists coming to join us in Bariloche. Check out the program!
https://yielding2019.sciencesconf.org/resource/page/id/9

Workshop on yielding phenomena in amorphous systems

We are organizing a STATPHYS27 satellite workshop in Bariloche, 2-5 July 2019, on yielding in amorphous materials and related phenomena. https://yielding2019.sciencesconf.org/  Save the date!

Our review accepted in Reviews of Modern Physics!

Great news! Our article “Deformation and flow of amorphous solids: Insights from elastoplastic models”
Alexandre Nicolas, Ezequiel E. Ferrero, Kirsten Martens, and Jean-Louis Barrat

Has been accepted for publication in RMP.

I have just become an Editor of Papers in Physics

I’m very happy and truly honored by the responsibility of becoming an Editor of Papers in Physics. This is a non-profit, accessible price, open-access journal, ran by physicists for physicists. Which further allows the “open review” treatment, that highlights not only the work done by authors but also by referees and editors.
The journal platform needs a touch of modernization, that’s true; but we’re working on it. The assignment of an official impact factor is expected soon and we will boost this journal up.

Our article “Magnetic domain wall creep and depinning: A scalar field model approach” is now published in PRE

Magnetic domain wall motion is at the heart of new magnetoelectronic technologies and hence the need for a deeper understanding of domain wall dynamics in magnetic systems. In this context, numerical simulations using simple models can capture the main ingredients responsible for the complex observed domain wall behavior. We present a scalar field model for the magnetization dynamics of quasi-two-dimensional systems with a perpendicular easy axis of magnetization which allows a direct comparison with typical experimental protocols, used in polar magneto-optical Kerr effect microscopy experiments. We show that the thermally activated creep and depinning regimes of domain wall motion can be reached and the effect of different quenched disorder implementations can be assessed with the model. In particular, we show that the depinning field increases with the mean grain size of a Voronoi tessellation model for the disorder.

Phys. Rev. E 97, 062122 – Published 11 June 2018
https://journals.aps.org/pre/abstract/10.1103/PhysRevE.97.062122

 

Our article “Damage accumulation in silica glass nanofibers” to appear in Nano Letters

The origin of the brittle-to-ductile transition, experimentally observed in amorphous silica nanofibers as the sample size is reduced, is still debated. Here we investigate the issue by extensive molecular dynamics simulations at low and room temperatures for a broad range of sample sizes, with open and periodic boundary conditions. Our results show that small sample-size enhanced ductility is primarily due to diffuse damage accumulation, that for larger samples leads to brittle catastrophic failure. Surface effects such as boundary fluidization contribute to ductility at room temperature by promoting necking, but are not the main driver of the transition. Our results suggest that the experimentally observed size-induced ductility of silica nanofibers is a manifestation of finite-size criticality, as expected in general for quasi-brittle disordered networks.

A nice collaboration with Silvia Bonfanti, Alessandro Sellerio, Roberto Guerra and Stefano Zapperi at CC&B Milano.
A ‘Just-Accepted’ version of the manuscript can be found here.

Magnetic domain wall creep and depinning: a scalar field model approach

Our new preprint on magnetic domain wall creep and depinning is available online!!!

Researcher position

I have started a new fresh year in a new office and a new desk, this time as an stable researcher of CONICET (the Argentinean National Research Council). I’m joining a group of excellent people, the condensed matter theory group, at Centro Atómico Bariloche (Argentina), a great spot to do science. I’m grateful to the group for the welcoming and to all my previous hosts for a very soft and enriching postdoc path to my actual position. Thanks!

Centro Atómico Bariloche (some time ago)