MPI-FKF homepage > Keimer's department
Physics of strongly correlated electron systems
Our department uses neutron and x-ray diffraction and spectroscopy, optical spectroscopy, and Raman scattering, supported by various supplementary methods, to explore the structure and dynamics of materials with strong electron correlations. Topics of particular current interest include the interplay between spin, charge, and orbital degrees of freedom in transition metal oxides; mechanisms of unconventional superconductivity in solids; and quantum many-body physics at oxide interfaces. We strongly believe that close collaboration between experimentalists and theorists is essential for progress in this field. To facilitate this interaction, a small theory group operates within the department. We also have a strong effort in the development of new spectroscopic methods, especially spectral ellipsometry with synchrotron radiation and neutron resonance spin-echo spectroscopy. To this end, we operate experimental facilities at the ANKA synchrotron in Karlsruhe and at the FRM-II research reactor in Garching, in addition to our in-house laboratories. The recently commissioned TRISP spectrometer at the FRM-II allows the determination of the lifetimes of collective excitations in solids with unprecedented accuracy.
Three-phase competition in underdoped YBa2Cu3O6+xResonant x-ray scattering experiments on highly ordered 'Ortho-II' YBa2Cu3O6.55 and Zn-substituted YBa2Cu3O6.6 revealed a three-phase competition between spin-modulated,charge-modulated, and superconducting states in underdoped cuprate superconductors.
S. Blanco-Canosa et al., Phys. Rev. Lett., 2013
Wolfram-Prandl-Prize 2012The leader of the neutron spectroscopy group Dr. Dmytro Inosov is this year's laureate of the Wolfram-Prandl-Prize for his outstanding work on iron-based high-temperature superconductors.
Official announcement (in German)
A density-wave order that competes with superconductivityUsing resonant x-ray scattering we obtained the unambiguous evidence for long-range incommensurate charge-density-wave fluctuations competing with superconductivity in underdoped (Y,Nd)Ba2Cu3O6+x.
G. Ghiringhelli et al., Science, 2012
Electron-phonon coupling in oxide superlatticesRaman spectroscopy reveals a long-range transfer of electron-phonon coupling between YBa2Cu3O7 and La2/3Ca1/3MnO3 layers in oxide superlattices.
N. Driza et al., Nature Materials, 2012
Magnetic resonant mode in CeB6Using inelastic neutron scattering, we have found a magnetic exciton mode in the non-superconducting heavy-fermion metal CeB6, resembling resonant magnetic excitations in unconventional superconductors.
G. Friemel et al., Nature Communications, 2012
Emergent phenomena at oxide interfacesA review article in Nature Materials discusses recent advances in understanding novel interface states that arise in oxide heterostructures due to the charge, spin and orbital reconstruction effects.
H. Y. Hwang et al., Nature Materials, 2012
Magnetic resonant mode in the Rb2Fe4Se5 superconductorA resonant magnetic excitation in the Rb-245 iron-selenide superconductor has been discovered at a wave vector, which differs from the ones characterizing magnetic resonant modes in other iron-based superconductors.
J. T. Park et al. Phys. Rev. Lett., 2011
G. Friemel et al. Phys. Rev. B (R), 2012