"Professeur Chargée de Cours" at Ecole Polytechnique
Research group : Condensed Matter
Head of the team "Condensed matter" at CPHT
|Address||CPHT, Ecole Polytechnique, 91128 Palaiseau cedex, France|
|Phone number||01 69 33 42 77|
|Fax number||01 69 33 49 49|
|Office||"Aile zéro", Office 1007|
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
Delange P, Backes S, van Roekeghem A, Pourovskii L, Jiang H, Biermann S.
Novel Approaches to Spectral Properties of Correlated Electron Materials: From Generalized Kohn-Sham Theory to Screened Exchange Dynamical Mean Field Theory.
Journal of the Physical Society of Japan 2018;87(4):041003.
Martins C, Lenz B, Perfetti L, Brouet V, Bertran F, Biermann S.
Nonlocal Coulomb correlations in pure and electron-doped Sr2IrO4: Spectral functions, Fermi surface, and pseudo-gap-like spectral weight distributions from oriented cluster dynamical mean-field theory.
Physical Review Materials 2018;2(3):032001.
Ayral T, Biermann S, Werner P, Boehnke L.
Influence of Fock exchange in combined many-body perturbation and dynamical mean field theory.
Physical Review B 2017;95(24):245130.
Delange P, Biermann S, Miyake T, Pourovskii L.
Crystal-field splittings in rare-earth-based hard magnets: An ab initio approach.
Physical Review B 2017;96(15):155132.
Fink J, Rienks EDL, Thirupathaiah S, Nayak J, van Roekeghem A, Biermann S, et al.
Experimental evidence for importance of Hund's exchange interaction for incoherence of charge carriers in iron-based superconductors.
Physical Review B 2017;95(14):144513.
Hirayama M, Miyake T, Imada M, Biermann S.
Low-energy effective Hamiltonians for correlated electron systems beyond density functional theory.
Physical Review B 2017;96(7):075102.
Martins C, Aichhorn M, Biermann S.
Coulomb correlations in 4d and 5d oxides from first principles-or how spin-orbit materials choose their effective orbital degeneracies.
Journal of Physics-Condensed Matter 2017;29(26):263001.
Panda SK, Jiang H, Biermann S.
Pressure dependence of dynamically screened Coulomb interactions in NiO: Effective Hubbard, Hund, intershell, and intersite components.
Physical Review B 2017;96(4):045137.
Richard P, van Roekeghem A, Lv BQ, Qian T, Kim TK, Hoesch M, et al.
Is BaCr2As2 symmetrical to BaFe2As2 with respect to half 3d shell filling?
Physical Review B 2017;95(18):184516.
Seth P, Peil OE, Pourovskii L, Betzinger M, Friedrich C, Parcollet O, et al.
Renormalization of effective interactions in a negative charge transfer insulator.
Physical Review B 2017;96(20):205139.
Seth P, Hansmann P, van Roekeghem A, Vaugier L, Biermann S.
Towards a First-Principles Determination of Effective Coulomb Interactions in Correlated Electron Materials: Role of Intershell Interactions.
Physical Review Letters 2017;119(5):056401.
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, École 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 — PhotoWorkshop on Ab Initio Methods for Correlated Spintronics Materials, Mont Saint Odile, 2004 School on "Electronic Structure Calculations and Correlated Materials", Les Houches, 2006
- Head of the team "Condensed matter" at CPHT