Regensburg 2000 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 20: Quantenphasenüberg
änge
TT 20.2: Vortrag
Donnerstag, 30. März 2000, 12:30–12:45, H18
Anomalous Low Temperature States in CeNi2Ge2 and YbRh2Si2 — •M. Grosche1, S. Mederle1, P. Agarwal2, O. Trovarelli1, S. Julian2, P. Gegenwart1, C. Langhammer1, J. Sichelschmidt1, R. Borth1, C. Geibel1, G. Sparn1, G. Lonzarich2, and F. Steglich1 — 1MPI-CPfS, Bayreuther Str. 40, 01187 Dresden — 2Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, UK
The study of 3d- and 4f-electron compounds on the threshold of magnetism has brought to light a number of ‘strange metals’ which appear to defy the conventional description of the metallic state in terms of well-defined fermionic and bosonic excitations. The pure compounds CeNi2Ge2 and YbRh2Si2 display nearly linear temperature dependences of the resistivity and a strongly temperature-dependent C/T over a wide range even at ambient pressure and are therefore particularly suited for a detailed investigation of this curious low temperature state. Both materials undergo further phase transitions under pressure or chemical substitution, which give rise to rich and interesting phase diagrammes. The normal state in the two materials and its evolution with hydrostatic pressure and magnetic field are discussed in the light of current theories of quantum critical behaviour.