logo-img
Materials Growth & Measurement Laboratory

Czech open access research infrastructure

MGML Dashboard

Submit a proposal!
Home
Event

Seminar: Petr Doležal

  • Petr Doležal: Physical and structural properties of LaPd2Al2
  • 25. 1. 2017, 14:30
  • lecture room F2, first floor Ke Karlovu 5
  • more information
Abstract:

(Ce,La)Pd2Al2 compounds crystallize in the tetragonal structure with the structural type CaBe2Ge2, space group P4/nmm (129) and undergoes a structural phase transition from the tetragonal to the orthorhombic structure with space group Cmme (67) [1]. The structural instability of (Ce,La)Pd2Al2 compounds at low temperatures is frequent behaviour for materials crystallizing in the CaBe2Ge2 structural type. The distortion at low temperatures is observed in e.q. CeNi2Sn2 [2], CePt2Ge2 [3], (Ce, La)Pd2Ga2 [4]. Moreover, CePd2Al2 compound is one of few materials where magnetoelastic coupling was observed [1] and recent studies show that structural details and phase purity of samples could play a significant role.

      LaPd2Al2 is a nonmagnetic compound which becomes superconducting when cooling below 1.88(3) K [5]. The superconducting properties of LaPd2Al2 and a broader series of LaPd2Al(2-x)Gax compounds exhibit deviations from behaviour predicted by the BCS theory [5]. The specific heat and electrical resistivity measurements revealed a non-exponential temperature dependence of electronic contribution to specific heat below the TSC, a positive curvature of Bc2(T) and a value of ΔCel/(γTSC) = 1.1 which is lower than 1.43 predicted by BCS theory. This behaviour is similar to that which is typical for non-conventional or non-centrosymmetric superconductors and keep the interest although the TSC does not belong to the highest one.

The presented study is mainly focused on single crystal preparation of non-congruently growing LaPd2Al2 phase and its characterization.  Transport and specific heat measurements will be discussed, too.

[1] L. C. Chapon, E. A. Goremychkin, R. Osborn, B. D. Rainford, S. Short, Magnetic and structural instabilities in CePd2Al2 and LaPd2Al2, Physica B 378380 (2006) 819820.

[2] R. V. Skolozdra, V. M. Mandzyk, Y. K. Gorelenko, V. D. Tkachuk, Crystal-structure and properties of RNi2Sn2 compounds, Fizika Metallov i Metallovedenie 52 (1981) 966-970.

[3] N. D. Mathur, C. D. Frost, CeIr2Ge2, a new heavy-fermion compound, Journal of Alloys and Compounds 215 (1994) 325-328.

[4] J. Kitagawa, M. Ishikawa, Magnetic properties and structural phase transition of CePd2Ga2 with CaBe2Ge2-type structure, Journal of the Physical Society of Japan 68 (1999) 2380-2383.

[5] M. Klicpera, J. Pásztorová, P. Javorský, Superconductivity in LaPd2Al(2-x)Gax compounds, Superconducto Science and Technology 27 (085001) (2014) 1-6.