Dresden 2011 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 23: CE: Quantum-Critical Phenomena 2
TT 23.8: Vortrag
Dienstag, 15. März 2011, 12:30–12:45, HSZ 105
Field-induced gap in a quantum spin-1/2 chain in a strong magnetic field — •M. Ozerov1, J. Wosnitza1, E. Čižmár2, R. Feyerherm3, S.R. Manmana4,5, F. Mila5, and S.A. Zvyagin1 — 1Hochfeld-Magnetlabor Dresden, Forschungszentrum Dresden-Rossendorf, Dresden, Deutschland. — 2Centre of Low Temperature Physics, P.J. Šafárik University, Košice, Slovakia. — 3Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany. — 4JILA, Department of Physics, University of Colorado, Boulder, Colorado, USA. — 5Institute of Theoretical Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
Magnetic excitations in copper pyrimidine dinitrate, a spin-1/2 antiferromagnetic chain with alternating g-tensor and Dzyaloshinskii-Moriya interaction, that exhibits a field-induced spin gap, are probed by means of pulsed-field electron spin resonance spectroscopy. In particular, we report on a minimum of the gap in the vicinity of the saturation field Bsat = 48.5 T associated with a transition from the sine-Gordon region (with soliton-breather elementary excitations) to a fully spin-polarized state (with magnon excitations). This interpretation is fully confirmed by quantitative the agreement with DMRG calculations for a spin-1/2 Heisenberg chain with staggered transverse field.
Part of this work has been supported by EuroMagNET under the EU contract N.228043.