- Mgr. Milan Klicpera: Vibron states in tetragonal Ce-based compounds
- 30. 10. 2013, 14:00
- Seminar room KFM, first floor Ke Karlovu 5
- more information
Abstract:
Cerium intermetallic compounds stay in the foreground of interest already a few decades. Such physical phenomena as magnetic ordering at very low temperatures, valence fluctuations, heavy-fermion behavior or unconventional superconductivity were found and studied so far. The exceptional and often exotic behavior of these compounds originates in the vicinity of the energy of the cerium 4f shell level to the 5d and 6s levels. The different magnetic properties then arise mainly from the competition between the long-range magnetic order of the RKKY type and the screening of the localized cerium 4f moments by conduction electrons. The tetragonal compounds CeTX3 or CeT2X2, where T is a transition d-metal and X is a p-metal, exhibit various ground states and phenomena depending on the actual chemical composition and form model family of Ce-based intermetallics for systematic study of above mentioned phenomena. The electron-phonon (e-p) interaction is very often neglected in many materials because only the subtle results of this interaction are observed. Nevertheless, there are many materials in which the e-p interaction cannot be neglected, for example in BCS superconductors. Further, the strong interaction between crystal field and phonon modes has not been investigated in details. This type of interaction leads to the formation of vibron quasi-bound state, which has been observed as an additional peak in the energy spectra of several Ce-based intermetallic compounds, e.g. CeAl2, CePd2Al2 or recently CeCuAl3.
The presented results are focused on electronic properties of CeCuAl3 and CePd2(Al,Ga)2 compounds studied by means of magnetization, specific heat and electrical resisitivity; the neutron diffraction experiments performed on CeCuAl3 and CePd2Ga2 compounds; and inelastic neutron scattering experiment provided on compounds from Ce(Cu,Al)4 series. P. Thalmeier, P. Fulde, Phys. Rev. Lett. 49 (1982) 1588. M. Loewenhaupt, U. Witte, J. Phys.: Cond. Matt. 15 (2003) S519. L.C. Chapon, E.A. Goremychkin, R. Osborn, B.D. Rainford, S. Short, Physica B 378-380 (2006) 819. D.T. Adroja, A. del Moral, C. de la Fuente, A. Fraile, E. A. Goremychkin, J.W. Taylor, A. D. Hillier, F. Fernandez-Alonso, Phys. Rev. Lett. 108 (2012) 216402. J. Kitagawa, M. Ishikawa, J. Phys. Soc. Japan 68 (1999) 2380-2383.