Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 17: Heavy Fermions
TT 17.5: Vortrag
Mittwoch, 28. März 2007, 15:00–15:15, H18
Larmor diffraction study of the thermal expansion of URu2Si2 under high pressure — •Philipp Niklowitz1, Christian Pfleiderer1, Thomas Keller2,3, and John Mydosh4 — 1Physik Department E21, Technische Universität München, 85748 Garching, Germany — 2Max-Planck-Institut für Festkörperforschung, 70569 Stuttgart, Germany — 3ZWE FRMII, Technische Universität München, 85748 Garching, Germany — 4II. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany
The metallic rare-earth system URu2Si2 shows two transitions at zero pressure: at T0≈ 17.5 K a strong peak in the heat capacity indicates the transition to an unknown so-called hidden order (HO) state; the HO state might be relevant to explain the occurance of a superconducting state at Ts≈ 1.4 K. A key to the HO state might be the large-moment AF state, to which the HO state is transformed under pressure. The pressure dependence of T0 is surprisingly weak across the pressure induced phase change and it is interesting to follow the pressure evolution of thermodynamic quantities.
We have studied the pressure evolution of the thermal expansion from zero pressure to 20 kbar and in a wide temperature range down to 3 K. Larmor diffraction experiments have been performed on a high quality single crystal of stoichiometric URu2Si2. In particular, we present in detail the pressure evolution of the signature of T0 in the thermal expansion of the a- and c-axis. Here, Larmor diffraction proves to be a very reliable technique for high precision measurements of the lattice constants.