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TT: Fachverband Tiefe Temperaturen
TT 4: CE: Quantum-Critical Phenomena 1
TT 4.1: Vortrag
Montag, 14. März 2011, 10:30–10:45, HSZ 201
Larmor diffraction studies on the ferromagnetic superconductor UGe2 — •Robert Ritz1, Dmitry Sokolov2, Thomas Keller3, Andrew D. Huxley2, and Christian Pfleiderer1 — 1Physik Department E21, TU München, D-85748 Garching, Germany — 2School of Physics and Astronomy, and Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh EH9 3JZ, UK — 3MPI für Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany
Larmor diffraction (LD) is a novel technique based on the Larmor precession of polarized neutrons that surpasses the resolution of conventional scattering methods by two orders of magnitude [1,2,3]. For a long time it was thought that it is not possible to measure LD on systems with depolarizing properties, such as ferromagnets. We present thermal expansion measurements under pressure by means of Larmor diffraction (LD) on the superconducting Ising ferromagnet UGe2. LD allowed us to measure magnetization and thermal expansion under pressure in the same setup and hence to directly compare transition temperatures. We found that the thermal expansion near TX, the transition between two ferromagnetic phases which is believed to drive superconductivity, shows a clear transition in the b- and c-axis under pressure at a temperature a few K higher than for the a-axis and the ferromagnetic Bragg peak. We are considering different mechanisms how this may be connected with the superconductivity in UGe2.
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C. Pfleiderer et al., Science 316, 1871 (2007)