Specific Heat at the Spin-Peierls Transition in CuGeO_3 Under Magnetic Fields up to 22 TesSa

摘要

We report on heat capacity measurements of the spin-Peierls compound CuCJeO s under magnetic fields between 0 and 22 teslas. We have determined the magnetic phase diagram between the three different phases (V = uniform, I incommensurate, D = dimerise.d) of this .system, unknown up to now far >14 T, and which can be well interpreted within the Bartree-Fock approximation. We have studied the 2nd order phase transition for H = const. at the crossing of D-U and I-U phases. The spin-Feierls-transition gives rise (