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Schlagwörter:
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Zusammenfassung:
We present an investigation of the spin-Peierls transition at T(sp) =
14.5 K in polycrystalline CuGeO(3) through specific-heat and
thermal-expansion measurements. Clear second-order phase-transition
anomalies are found in both properties at T(SP), although only a small
entropy of S approximate to 0.1 Rln2 is released at the transition. Most
of the entropy is released at T(SP) < T < 150 K, where the temperature
dependence of the magnetic contribution to the specific heat as well as
the thermal expansion exhibit extrema at T* approximate to 40 K. These
are caused by one-dimensional antiferromagnetic fluctuations along the
Cu chains, possibly accompanied by structural fluctuations. Using
Ehrenfest's relation, a hydrostatic pressure coefficient (partial
derivative T(SP)/partial derivative)(p))(p) --> O approximate to (0.45
+/- 0.06) K/kbar is derived.
