- Petr Doležal: Structural phase transitions in (Ce,La)Pd2Al2-xGax series
- 25. 3. 2015, 14:50
- lecture room F2, first floor Ke Karlovu 5
- more information
Abstract:
Tetragonal CeT2X2 compounds (T: d-element and X: p-element) reveal such physical properties as pressure-induced superconductivity, valence fluctuating phenomena or strong crystal field exciton-phonon coupling leading to the formation of new quantum state in CePd2Al2 [1]. The CeT2X2 compounds generally crystallize in centrosymmetric ThCr2Si2- or CaBe2Ge2-types of tetragonal crystal structure. Compounds crystallizing in CaBe2Ge2-type structure are frequently reported to undergo transition to structures with lower-symmetry at low temperatures. CePd2Al2 and CePd2Ga2 compounds exhibit structural transition from tetragonal CaBe2Ge2-type structure to orthorhombic structure at 13.5 K [1] and to triclinic structure at 125 K [2], respectively. Moreover the same structural phase transition was observed also in their non-magnetic La analogues [1,2].
Presented study focuses on the development of structural transitions in (Ce,La)Pd2Al2-xGax compounds with Ga doping. The type of transition and transition temperature within the series were investigated by low-temperature powder X-ray diffraction. Complementary, the measurements of magnetization, specific heat, electrical resistivity and electrical resistivity under hydrostatic pressure were performed on selected concentrations, including the CePd2Al2 single crystal, and are discussed from the thermodynamic point of view.
[1] L.C. Chapon, E.A. Goremychkin, et al., Physica B 378-380, 819 (2006)
[2] J. Kitagawa, M. Ishikawa, Journal of the Physical Society of Japan, 2380-2383, 68 (1999)