Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 20: Correlated Electrons - Poster Session
TT 20.29: Poster
Mittwoch, 28. März 2007, 14:00–17:45, Poster A
Low-temperature study of an S =1/2 antferromagnetic Heisenberg chain close to the field-induced quantum critical point — •K. Remović-Langer1, Y. Tsui1, U. Tutsch1, V. Pashchenko1, B. Wolf1, A. V. Prokofiev2, and M. Lang1 — 1Physikalisches Institut, J. W. Goethe-Universität, Frankfurt(M), Germany — 2Institut für Festkörperphysik, Technische Universität Wien, Wien, Austria
We present magnetic susceptibility, electron spin resonance (ESR), and magnetocaloric effect (MCE) measurements of the compound [Cu(µ-ox)(4-apy)2(H2O)]n 1. Magnetic susceptibility measurements, performed in the temperature range from 50 mK up to 300 K, can be interpreted within an uniform 1D Heisenberg model with a small antiferromagnetic exchange interaction of J/kB ≈ ( 3.14 ± 0.1 )K. The magnetization M(B) was obtained by integrating the susceptibility data. At the lowest temperatures, M(B) saturates at a field µ0Hsat = (4.3 ± 0.1) T. The angular dependence of the resonance absorption line, obtained from ESR measurements, reveals the magnetic anisotropy of the S = 1/2 copper ions. MCE measurements were performed at low temperatures and at fields in the vicinity of the saturation field which, at zero-temperature, marks a quantum phase transition with intriguing magnetocaloric properties2. The significance of the MCE results will be discussed.
1A. V. Prokofiev et. al. , submitted to Crystal Research and Technology. 2L. Zhu et. al., Phys. Rev. Lett. 91, 066404 (2003); M. E. Zhitomirsky, A. Honecker, J. Stat. Mech.: Theor. Exp (2004) P07012.