Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 25: Correlated Electrons - Poster Session
TT 25.7: Poster
Mittwoch, 29. März 2006, 14:30–18:30, P1
Determination of the phase diagram of the spin ladder system (C5H12N)2CuBr4 by caloric and magnetic measurements — •Klaus Kiefer1, Christian Rüegg2, Thomas Wand1, Michael Meißner1, Des McMorrow2, Karl Krämer3, Daniel Biner3, and Hans U. Güdel3 — 1BENSC, Hahn-Meitner-Institut Berlin — 2Department of Physics and Astronomy, University College London, UK — 3Universität Bern
The phase diagram of the S=1/2 spin ladder system (C5H12N)2CuBr4 was determined by measurements of the specific heat, the magnetocaloric effect and the magnetisation in magnetic fields up to 14.5 T. The exponential temperature dependence of the low temperature specific heat clearly reveals the existence of an energy gap between the non magnetic ground state and the magnetic excitations. The field driven closing of this gap is found to occur at about 7 T. In the Luttinger liquid regime the expected linear temperature dependence of the specific heat was confirmed. Down to the lowest accessible temperature of 0.3 K no additional transition to long-range 3D-order could be detected.