Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 16: CE: Quantum-Critical Phenomena 1
TT 16.9: Vortrag
Dienstag, 23. März 2010, 16:00–16:15, H19
Vibrating Coil Magnetometry of quantum criticality in the Ising Ferromagnet LiHoF4 — •Stefan Legl1, Bastien Dalla Piazza2, Karl Krämer3, Henrik Ronnow2, and Christian Pfleiderer1 — 1Physik Department E21, Technische Universität München, James-Franck-Strasse, D-85748 Garching, Germany — 2EPFL, CH-1015 Lausanne, Switzerland — 3Department of Chemistry & Biochemistry, University of Bern, CH-3012 Bern, Switzerland
LiHoF4 develops Ising ferromagnetism below a Curie temperature, TC=1.54 K. The easy-axis magnetization of LiHoF4 has recently attracted great interest as a testing ground for theoretical studies of domain formation in Ising systems. This is contrasted by the properties of LiHoF4 for magnetic field applied transverse to the Ising axis, where susceptibility measurements suggest the existence of a quantum critical point at a critical field Hc=4.90 T. An outstanding issue in studies of LiHoF4 are direct measurements of the magnetization parallel to an applied magnetic field, M∥, as the principle order parameter of the ferromagnetic state. We have used a newly developed vibrating coil magnetometer (VCM) as combined with a top loading dilution refrigerator for measurements of the field and temperature dependence of M∥ in LiHoF4 down to mK temperatures. We present first results of our measurements and a critical discussion of the agreement and disagreement with previous work.