Crystal structure and Kondo lattice behavior of CeNi9Si4

Autor(en)

Herwig Michor, Stefan Berger, M El-Hagary, Christoph Paul, Ernst Bauer, Gerfried Hilscher, Peter Franz Rogl, Gerald Giester

Abstrakt

We have studied the crystal chemistry and magnetic, thermodynamic, and transport properties of RNi9Si4 with R = La and Ce. These compounds crystallize in a fully ordered tetragonal (space group 14/mcm) variant of the cubic NaZnl3 type. The low-temperature properties characterize CeNi9Si4 as a Kondo lattice with a large Sommerfeld value y= 155(5) mJ/mol K2 as compared to ? = 33 mJ/mol K2 of Pauli paramagnetic LaNi9Si4. The temperature dependencies of the specific heat and susceptibility are well described by the degenerate (J = 5/2) Coqblin-Schrieffer model with a characteristic temperature T0 ? 180 K. The large Ce-Ce spacing in CeNi9Si4 (dCe-Ce˜5.6 A°) implies very weak Ce-Ce intersite exchange interactions which is corroborated by the thermoelectric power S(T) showing close agreement with theoretical results of the degenerate Anderson lattice without intersite interactions. CeNi9Si4 appears to be a model type Kondo lattice system with To >?CEFŸTRKKY where To, ?CEF (crystalline electric field), and TRKKY (Ruderman-Kittel-Kasuya-Yosida) are the characteristic energy scales of the Kondo interaction, crystal field splitting, and Ce-Ce intersite exchange coupling, respectively. CeNi9Si4 shows a remarkably low ratio A/?2 = 0.83 (8) × 10-6 œ? cm(molK/mJ)2 which is one order-of-magnitude smaller than the usual Kadowaki-Woods ratio of heavy-fermion systems.

Organisation(en)

Institut für Physikalische Chemie, Institut für Mineralogie und Kristallographie

Externe Organisation(en)

Technische Universität Wien

Journal

Physical Review B

Band

67

Seiten

2244281-22442810

Anzahl der Seiten

20198530

ISSN

1098-0121

Publikationsdatum

2003

Peer-reviewed

Ja

ÖFOS 2012

1051 Geologie, Mineralogie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/1dfed5c5-5152-4bc8-b526-f72d54bd1104