Regensburg 2004 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
TT: Tiefe Temperaturen
TT 7: Korrelierte Elektronen: Schwere Fermionen
TT 7.7: Vortrag
Montag, 8. März 2004, 16:15–16:30, H19
YbIr2Si2− A new Yb−based Heavy Fermion System situated close to Quantum Critical Point — •Z. Hossain, C. Geibel, H. Jeevan, F. Weickert, P. Gegenwart, T. Lühmann, and F. Steglich — Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
While YbRh2Si2 is presently subject of thorough investigation motivated by its proximity to a quantum phase transition, the isoelectronic compound YbIr2Si2 has not yet been investigated. We have synthesized polycrystalline and single crystalline samples of YbIr2Si2 and investigated their physical properties. Depending on synthesis conditions the samples take either body-centred (ThCr2Si2 structure- I-type) or primitive tetragonal (CaBe2Ge2 structure- P-type) structure. P-type sample shows AF order below 700 mK. I-type sample does not show any signature of magnetic order down to 100 mK. The magnetic susceptibility for this sample is highly anisotropic with effective moment close to that expected for Yb3+ ions. The resistivity is nearly temperature independent at high temperature followed by a rapid decrease below 100 K similar to Kondo lattice/heavy fermion system. The resistivity does not show any anomaly due to either magnetic or superconducting transition down to 20 mK. Further, the resistivity at low temperature follows ρ(T) = ρ0 + ATn with n =1.3 instead of n = 2 expected from Fermi Liquid theory. The specific heat is also Non-Fermi-Liquid (NFL) type as C/T continues to increase with decreasing T down to 350 mK where C/T = 0.6 J/(mol K2). Thus, I-type YbIr2Si2 is a new heavy fermion compound situated close to the quantum critical point and exhibits NFL behaviour.