Research Group
Strongly Correlated Quantum Materials






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Silke Biermann

Centre de Physique Théorique (CPHT)
École Polytechnique
91128 Palaiseau Cedex
Tel.: +33-1-6933-4277
Fax.: +33-1-6933-4949
Professeur chargée de cours ("associate professor")
at ɉcole Polytechnique


Research Interests

My research is concerned with strong electronic Coulomb interactions in solid state systems. The key questions are: What's the role of strong Coulomb interactions, and what consequences can they have? How to handle them within solid state theory?

The first question cannot be discussed without mentioning the following points:
  • Metal-insulator transitions
  • Spectral weight transfer from quasi-particle excitations to incoherent contributions
  • Interplay of structural, orbital and spin degrees of freedom in correlated materials
  • Non-local effects of Coulomb correlations
During the last 40 years Density Functional Theory (DFT) within the local density approximation (LDA) has revolutionized the field of electronic structure calculations. Still, the materials I am particularly interested in are precisely those for which this theory is not sufficient. In strongly correlated systems Coulomb many-body effects cannot be expressed within an effective single-particle theory; to calculate dynamical correlations Dynamical Mean Field Theory (DMFT) is a useful tool. Combining DFT and DMFT (which leads to the so-called "LDA+DMFT" method) nowadays allows to calculate the electronic structure of strongly correlated materials (nearly) from first principles (i.e. without adjustable parameters).

Relevant methodological questions include:
  • Developments within LDA+DMFT, e.g. concerning impurity model solvers, basis sets
  • Cluster extensions of DMFT
  • Some fundamental questions (e.g.: What's U in a solid? )
  • Developments of alternative (first principles) approaches (the word "nearly" is missing now!), such as GW+DMFT

  • Materials that are good test cases are e.g. the following:
  • transition metals
  • their oxides (e.g. VO2, vanadates, titanates) and sulfides
  • lanthanides and actinides
  • quasi-1d systems
  • Recently, I found myself also doing quite a lot of work on iron-oxypnictides and related compounds, such as LaFeAsO, FeSe, or BaFe2As2.


    Some Recent Publications


    Curriculum Vitae


    Ph.D., Physics, University of Cologne, Germany, 2000
    Diploma degree, Physics, University of Cologne, Germany, 1996
    Maîtrise, Physics, Magistère Interuniversitaire de Physique des Universités Paris VI, VII, XI, XIII et
    de l'École Normale Supérieure Paris, France, 1994
    Prediploma degrees, Physics and Mathematics, University of Cologne, Germany, 1993


    Since September 2003
    Professeur Chargée de Cours ("Associate professor") at École Polytechnique, France
    Affiliation: Centre de Physique Théorique, ɉcole Polytechnique, Palaiseau, France.
    September 2000 - August 2003
    Postdoctoral fellow/CNRS associate researcher at Laboratoire de Physique des Solides Université Paris Sud and
    Laboratoire de Physique Théorique de l'Ecole Normale Supérieure Paris, France
    April 1997 - August 2000
    Ph.D. student at Juelich Research Centre, Germany
    July 1996 - March 1997
    Visiting scholar at Texas A&M University, Texas, USA

    Organisation of conferences and schools

    Workshop "Electronic Structure of Correlated Materials" and Mid-Term Review of the RTN "f-Electron Materials", Paris, 2004 -- Photo
    Workshop on Ab Initio Methods for Correlated Spintronics Materials, Mont Saint Odile, 2004
    School on "Electronic Structure Calculations and Correlated Materials", Les Houches, 2006


    LPS Orsay
    Studienstiftung des deutschen Volkes