Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 2: Symposium: High Magnetic Field Phenomena in Low Dimensional Magnets
TT 2.4: Vortrag
Montag, 25. Februar 2008, 11:00–11:15, H 0104
High-field properties of a critical frustrated chain cuprate: Li2ZrCuO4 — •Stefan-Ludwig Drechsler1, Rüdiger Klingeler1, Natalia Tristan1, Norman Leps1, Johannes Richter2, Thomas Lorenz3, Olga Volkova4, Alexander Vasiliev5, and Bernd Büchner1 — 1IFW-Dresden, P.O. Box 270116, D-01171 Dresden, — 2Inst. f. Theoret. Physik, Universität Magdeburg — 3II. Physikal. Inst., Universität zu Köln — 4Inst. f. Electronics and Automatics, Moscow, Russia — 5Lomonosov University, Moscow, Russia
We report an unusual strong field dependence of the magnetic specific heat cp(T,H), the thermal expansion α(T,H), and the magnetization m(T,H) curve of the frustrated edge-shared chain cuprate Li2ZrCuO4 which is close to the quantum critical point between ferromagnetic and helical ordering [1]. The low-temperature peak of cp(T) is first down shifted for H< 9 T, then reaches a broad plateau before its position is up shifted at high fields H ≈ 30 T. The thermal expansion α changes its sign at about 9 T. The magnetization m(H) saturates at 15-20 T at low temperature well above the estimated saturation field Hs≈ 4.5 T for the 1D J1-J2–Heisenberg model pointing to a non-neglible influence of the interchain exchange in accord with estimates based on the dispersion of the LDA bands perpendicular to the chain direction. Possible scenarios for the deviation of the experimental cp(T,H) data at high fields from the predictions of the isotropic 1D J1-J2-Heisenberg model are briefly discussed.
[1] S.-L. Drechsler et al., Phys. Rev. Lett. 98, 077202 (2007).