Regensburg 2016 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 43: Correlated Electrons: f-Electron & Heavy Fermion Systems

TT 43.7: Vortrag

Mittwoch, 9. März 2016, 11:00–11:15, H20

Exchange field effect in the crystal field ground state of CeMAl₄Si₂ — •Kai Chen¹, Fabio Strigari¹, Martin Sundermann¹, Stefano Agrestini², Eric D. Bauer³, John L. Sarrao³, Joe D. Thompson³, Edwige Otero⁴, Arata Tanaka⁵, and Andrea Severing¹ — ¹University of Cologne, Cologne, Germany — ²Max Planck Institute for Chemical Physics of Solids, Dresden, Germany — ³Los Alamos National Laboratory, Los Alamos, US — ⁴Synchrotron Soleil,Gif-sur-Yvette Cedex,France — ⁵Hiroshima University, Higashi-Hiroshima,Japan

The crystal-field ground state wave functions of the tetragonal Kondo lattice materials CeMAl₄Si₂(M = Rh, Ir and Pt), as well as the crystal-field splittings, are determined with low temperature linear polarized soft x-ray absorption spectroscopy. Surprisingly, at T < 20 K, which is far below the first excited crystal-field level at 200 K, a change in linear dichroism was observed that cannot be accounted for by population of crystal-field states. Adding an exchange field to the ionic full multiplet calculations below 20 K leads to a splitting to the ground state doublet and modification of J_z admixture, thus accounting for the change in low temperature linear dichroism. The direction of the required exchange field is parallel along c-axis for the antiferromagnetic Rh and Ir compounds, and perpendicular to c-axis for ferromagnetic CePtAl₄Si₂.