Speaker
Prof.
Jochen Litterst
(TU Braunschweig)
Description
The spinel FeCr2S4 has been studied intensely during the past for its magnetic and orbital ordering properties. Ferromagnetic coupling occurs between the B-site Cr. The A-site Fe2+ couples antiferromagnetically to the Cr sublattice. The ferrimagnetic order is driven by the Cr coupling. Recent muon spin rotation data [1] give strong evidence that the earlier claimed magnetic structures are in fact more complex. The collinear ferrimagnetism found between the Curie temperature (165K) and 50K changes to an incommensurate, probably helical structure. Close to the ordering/reorientation temperatures considerable spin disorder is detected. Below 10K orbital order is found.
Several attempts have been reported for an interpretation of the iron hyperfine spectra based on the assumption of collinear magnetic structures. We present new experimental Mössbauer spectroscopic data and a new strategy of analysis taking into account the magnetic correlation results obtained from muon spin rotation. The influence on spectral shape by changing Jahn-Teller dynamics will be discussed. Special emphasis is given to the interpretation of the spectra close to the spin reorientation near 50K and near the orbital ordering transition indicating the splitting of the orbital ground state of Fe2+ and a possible formation of an orbital glass state.
[1] G. M. Kalvius et al., J. Phys.: Condens. Matter 22 (2010) 052205
Primary authors
Dr
Alexander Krimmel
(Universität Augsburg)
Prof.
Alois Loidl
(Universität Augsburg)
Prof.
Fritz Wagner
(TU München)
Prof.
Jochen Litterst
(TU Braunschweig)
Ms
Josefin Engelke
(TU Braunschweig)
Prof.
Michael Kalvius
(TU München)
