Dresden 2006 – scientific programme
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TT: Tiefe Temperaturen
TT 3: Correlated Electrons: Quantum-Critical Phenomena
TT 3.4: Talk
Monday, March 27, 2006, 10:15–10:30, HSZ 301
Field-Induced Phase Transition in a Metalorganic Spin-Dimer System — •Y. Tsui1, A. Brühl1, K. Removic-Langer1, V. Pashchenko1, B. Wolf1, M. Lang1, G. Donath2, A. Pikul2, T. Kretz3, H.-W. Lerner3, M. Wagner3, A. Salguero4, T. Saha-Dasgupta4, B. Rahaman4, and R. Valenti4 — 1Physikalisches Institut, J.W. Goethe-Universität, Frankfurt, FOR-412, Germany — 2Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden, Germany — 3Institut für Anorganische Chemie, J.W. Goethe-Universität, Frankfurt, FOR-412, Germany — 4Institut für Theoretische Physik, J.W. Goethe-Universität, Frankfurt, FOR-412, Germany
We have investigated the field-induced magnetic order in a three-dimensional metalorganic spin-dimer system, C36H48Cu2F6N8O12S2 (TK91). The nature of the dimers and their couplings have been identified by first principles Density Functional Theory calculations. We have performed electron spin resonance, magnetic susceptibility, specific heat and thermal expansion measurements on both powder and single-crystal samples, in applied magnetic fields up to 12T and at temperatures down to ∼ 0.1K. Clear indications of a field-induced phase transition have been observed when the applied magnet field is above a temperature-dependent critical field Bc(T) ∼ 3T. A similar field-induced phase transition was also observed in an inorganic compound TlCuCl3. In case of TlCuCl3, the phase transition was interpreted as the Bose-Einstein condensation (BEC) of magnons. We propose TK91 as another possible model system to study the BEC of magnons.