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Material physics

Antoine Georges : Theorist of Condensed Matter

His theoretical works on condensed matter have won him the 2006 Agilent Technologies Europhysics prize. Antoine Georges is still keen on tracking explanations to the behavior of “high critical temperature” superconductors.

a georges

© Ph. Lavialle/Ecole Polytechnique


It may be due to the comings and goings of the electrons he studies, but the man also seems to be in perpetual motion. Antoine Georges has a flair for being both here–in his modern office at France's prestigious École Polytechnique–and there, essentially in the US to meet his peers. In France, he manages a basic research team at the Theoretical Physics Center,1 and for the past 15 years has been tracking “strongly correlated” electrons (i.e., electrons that are highly mutually dependent) in materials such as oxides. This includes vanadium and cobalt oxides as well as copper ones, materials that are “high critical temperature” superconductors–and “that still raise several fundamental questions.” Georges came up with a new theoretical approach to deal with these problems via calculations and digital simulations. For this work, he and three colleagues2 received the 2006 Agilent Technologies Europhysics prize3 awarded for research in condensed matter physics.

His early career as a scientist could have as easily taken him towards the field of biology. As a teenager, he often filched a few mice for dissection from his father's laboratory at Inserm (the French Institute of Health and Medical Research). But as his studies progressed, he was increasingly attracted by research on more quantitative matters. He studied at the Ecole Polytechnique to then work at the Theoretical Physics Laboratory of the École normale supérieure during the mid-80s. There, they were a small group of students operating with an unusual degree of freedom, and working like “free electrons” on all kinds of topics directly involved in the physics of disordered systems. The only requirements: To publish relevant articles and learn the quantum field theory, the unifying language for describing systems comprising a large number of interactive components. The experience anchored Georges's conviction that society must trust research scientists and their sense of responsibility.

In 1986, he decided to join CNRS, while staying at Ecole normale. It was that same year that Bednorz and Müller made their major discovery of “high critical temperature” superconductors, a revolutionary concept that fascinated the young research scientist. He set off for Princeton to learn about this new field in the laboratory of Philip W. Anderson, a “superstar of condensed matter physics, who offers very unusual explanations for those materials. Unfortunately, we had no suitable calculation methods.” Contrary to the methods preferred by many scientists, Georges was convinced that calculations were the key to understanding these materials. While working off the beaten path, he met Gabriel Kotliar, an Argentinean four years his senior who also had a background in statistical physics. Together, the scientists developed a new approach to mean fields, “which depends on the energy or time scale used, because in a correlated metal, electrons 'hesitate' between two types of behavior: They sit sensibly on atoms during short periods of time, and finally delocalize after longer periods.” The dynamical mean field theory (DMFT) was born, but it created quite a few waves within a community “reticent towards innovation in this pioneering field.” Nevertheless, after fifteen years of intensive work, their results are finally being used even for some practical applications.

But the physicist is first and foremost a theoretician. His extended detour through new calculation methods–and therefore new concepts–may eventually bring him closer to his initial goal: to unravel the mystery of very high temperature copper oxide superconductors. Having gained precious experience in this field, he joined École Polytechnique in 2003 to create a new team to study the “theory of materials with a strong quantum correlations.” The team focuses on electrons in solids, but also on “artificial solids, made of light and atoms, which can now be created through the extraordinary progress in quantum optics of cold atoms.” This is one of Georges' latest pet projects. He claims to be “happy in France for now, but ready to leave the country if scientific research is not perceived–and supported–as a priority.”

So far so good: Georges and his cosmopolitan team are among the worldwide leaders in this pioneering field.

 

Patricia Chairopoulos

Notes :

1. Centre de physique théorique (CNRS / École polytechnique joint lab).
2. Gabriel Kotliar, Dieter Vollhardt, and Walter Metzner.
3. www.agilent.com/contributions/europhysics.shtml

Contacts :

Antoine Georges
Centre de physique théorique, Palaiseau.
georges@cpht.polytechnique.fr


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