A heat capacity investigation of the soliton lattice in the high-field incommensurate phase of

¹ Centre de Recherches sur les Très Basses Températures and Laboratoire des Champs Magnétiques Intenses, Laboratoires associés à l'Université Joseph Fourier, CNRS BP 166, F-38042 Grenoble Cedex 9, France
² Bay Zoltán Foundation for Applied Research, Institute of Logistics and Production Systems Miskolc-Tapolca - Iglói u. 2. H-3519, Hungary
³ Institut für Tieftemperaturphysik - T. U. Dresden, D-01069 Dresden, Germany
⁴ Laboratoire de Chimie des Solides, URA 446 CNRS, Université Paris-Sud F-91405 Orsay Cedex, France

Received: 16 October 1998
Accepted: 18 March 1999

Abstract

We report on a heat capacity investigation of the spin-Peierls compound CuGeO₃ by magnetic field sweeps up to 27 T at fixed temperatures. In the dimerized phase the heat capacity exhibits a simple quadratic field dependence. In contrast, non-monotonous variations occur in the incommensurate phase, with characteristic plateaus separated by steps or smoother variations, depending on the quality of the samples. Such a plateau-type structure is attributed to the dynamics of solitons where a pinning mechanism blocks the continuous rearrangement of the soliton lattice driven by the magnetic field.