Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 19: Correlated Electrons: Low-dimensional Materials
TT 19.6: Vortrag
Dienstag, 28. März 2006, 15:15–15:30, HSZ 301
Magneto–elastic effects in Azurite — •Andreas Brühl1, Katarina Removic–Langer1, Yeekin Tsui1, Bernd Wolf1, Michael Lang1, and Jürgen Schreuer2 — 1Physikalisches Institut, J.W.Goethe–Universität Frankfurt — 2Institut für Mineralogie, J.W.Goethe–Universität Frankfurt, Frankfurt am Main
Quantum spin systems with frustration exhibit comprehensive phase diagrams with a variety of possible ground states. One of the simplest one-dimensional frustrated quantum systems is the S=1/2 diamond chain. According to recent theoretical calculations for the distorted diamond chain the ground state is either a ferrimagnetic phase, a dimerized phase or a spin liquid phase. So far, experimental work has been hampered by lacking appropriate compounds until recently, when Kikuchi et al. found that the natural mineral azurite (Cu3(CO3)2(OH)2) is a model substance for the distorted diamond chain. In this contribution we present results of magnetic susceptibility, thermal expansion and pulse field ultrasonic measurements on a high quality azurite single crystal. From the pronounced anomalies in the coefficient of thermal expansion as a function of temperature and the elastic constant as a function of magnetic field around the saturation field of 32 T, we infer an extraordinarily strong magneto–elastic coupling constant. We discuss our results in light of the different possible ground states that have been proposed for this material.