Michal Falkowski: Charge density wave behaviour in single-crystalline (La, Nd)Pt2Si2
Venue: lecture room F2, first floor, Ke Karlovu 5 - Prague 2
We have a pleasure to invite you to attend the joint seminar
of the Department of Condensed Matter Physics (DCMP)
and the Materials Growth and Measurement Laboratory (MGML) http://mgml.eu.
Charge density wave behaviour in single-crystalline (La, Nd)Pt2Si2
lecture given by:
Charles University, Faculty of Mathematics and Physics, DCMP, Ke Karlovu 5, 12116 Prague 2, Czech Republic
The seminar takes place in the lecture room F2
of the Faculty of Mathematics and Physics, Ke Karlovu 5, Praha 2
on Wednesday, 21.11. 2018 from 14:10
On behalf of the DCMP and MGML
Charge density waves (CDWs) are observed in many metallic conductors, especially in low-dimensional systems. Their existence was first predicted by Rudolf Peierls , who prophesied that for T=0K the CDWs would exist in an ideal one-dimensional chain of atoms, lowering the energy of the system and driving a reconstruction of the lattice. The Peierls transition (or sometimes the so-called the Peierls distortion) is an electronic instability in a one-dimensional crystal which occurs because of the particular geometry of the Fermi surface. The highly anisotropic topology of the Fermi surface in low-dimensional systems may favours the creation of a structural instability, therefore, a CDW can be defined as a modulation of the conduction electron density in a metal, associated with a modulation of the lattice atom positions . The occurrence of such a distortion in the periodic crystal lattice with an electronic disturbance may opens up a gap at the Fermi level, and such materials very often undergo a second-order metal-insulator (or metal-semimetal) transition below room temperature, as evidenced by a wide range of transport, magnetic, and specific heat studies.
Rare-earth intermetallic compounds REPt2Si2 that crystallize in the tetragonal CaBe2Ge2 structure (space group P4/nmm) show various ground states through the occurrence of magnetism (Sm , Eu , Gd , Tb , Dy , Ho , Er , Tm)Pt2Si2, superconductivity (Y , La , Lu )Pt2Si2, or strong electronic correlations that lead to the mixed valence (YbPt2Si2 ) and Kondo lattice (CePt2Si2 ) behaviour. Among the intermetallics, three compounds (La , Pr , Nd )Pt2Si2 seems to be particularly interesting due to possible CDW transition caused by a structural instability below room temperature. In my talk I will focus on presenting the most crucial results of my research for two single-crystalline compounds LaPt2Si2 and NdPt2Si2, by discussing thermodynamic (specific heat), thermal and electron transport (electrical resistivity, thermoelectric power, thermal conductivity) properties, as well as magnetic and crystallographic properties.
In collaboration with: P. Doležal, A.V. Andreev and L. Havela
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- Wednesday, 21 November 2018 14:10 - 15:10