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Strongly correlated f-electron systems

Strongly correlated f-electron systems provide a large variety of complex phase diagrams, and they often exhibit unusual magnetic properties. Due to the coupling and/or competition of electronic, structural and magnetic degrees of freedom, they are not only of general interest, but also open opportunities for specific applications by tuning parameters within this space.

Magnetically driven superconductivity has been a field of research here for several years, especially in relation to Heavy Fermion characteristics and quantum criticality.

Nevertheless, many systems do just not become superconducting, even being not very different from related superconductors, or they are magnetic analogs. One example is CeCu2Ge2, the magnetic counterpart of CeCu2Si2, where neither the high-field magnetic phase transition nor the magnetic excitation spectra are fully understood [1].

In addition, interactions between elementary excitations drive emergent functionalities and electronic instabilities such as multiferroic behavior, anomalous thermoelectric properties, polar order, or superconductivity. In cooperation with TU München (joint DFG funding) and Charles University Prague, we study non-centrosymmetric strongly correlated electron Ce-systems showing hybridization of crystal electric fields with phonons [2]. The focus is now on the influence of the structure on the hybridization effects and on their degree of universality.

Key characteristics of the neutron-scattering excitation spectraKey characteristics of the neutron-scattering excitation spectra of single-crystal CeAuAl3 observed in reciprocal space along Γ to M to S to Γ at T = 5 K. (A) Energy vs. reciprocal space map of CeAuAl3. 
Copyright: Forschungszentrum Jülich

References:

  1. P. Geselbracht, A. Schneidewind, M. Doerr, S. Granovsky, M. Rotter, M. Loewenhaupt, G. W. Scheerer, Z. Ren, and K. Prokeš, Magnetic phase diagram of CeCu2Ge2 up to 15 T: On the route to understand field-induced phase transitions, Phys. Rev. B 95, 214425 (2017)
  2. Čermák,  A. Schneidewind, B. Liu, M. M. Koza, and C. Franz,  Magnetoelastic hybrid excitations in CeAuAl3, Phys. Rev. B 98,174306 (2018)

Contact: 

Astrid Schneidewind
Phone:  +49 89 158860-749  
email: a.schneidewind@fz-juelich.de

ORCID

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