Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 31: Correlated Electrons - Low-dimensional Materials I

TT 31.8: Vortrag

Dienstag, 8. März 2005, 15:45–16:00, TU H2053

Field induced magnetic phase transition in Cs₂CuCl₄ as a magnon Bose-Einstein condensation — •Teodora Radu¹, Heribert Wilhelm¹, Viktor Yushankhai¹, Dmitry Kovrizhin², Radu Coldea³, Thomas Lühmann¹, and Frank Steglich¹ — ¹MPI für Chemische Physik fester Stoffe D-01187 Dresden, Germany — ²MPI für Physik komplexer Systeme D-01187 Dresden, Germany — ³Oxford Physics, Clarendon Laboratory Oxford, OX1 3PU, UK

We report on results of specific heat C(T) measurements on single crystals of the frustrated quasi-2d spin −1/2 antiferromagnet Cs₂CuCl₄ in the external magnetic field 0 T≤ B ≤ 12 T and in the temperature range 0.3 K<T<6 K. For different orientation of the applied magnetic field, B with respect to the crystallographic axes, the magnetic phase diagrams are obtained and compared with the previous neutron scattering results. For B∥ a, the magnetic phase transition near the critical field B_c≃ 8.44 T is treated as a magnon Bose Einstein condensation (BEC). In this context, the phase boundary T_N ∼ (B_c−B)^1/φ is described with the critical exponent φ ≃ 1.5. This result is discussed in terms of a simple mean-field theoretical study of the magnon BEC.