Abstract
Specific heat measurements have been performed in the coupled dimer system which has a singlet ground state with the excitation gap K. The cusplike anomaly indicative of the three-dimensional magnetic ordering was clearly observed in magnetic fields higher than the critical field corresponding to the gap The phase boundary determined by the present specific heat measurements coincides with that determined by previous magnetization measurements. The phase boundary can be described by the power law with This result supports the magnon Bose condensation picture for the field-induced magnetic ordering in [Nikuni et al., Phys. Rev. Lett. 84, 5868 (2000)].
- Received 25 October 2000
DOI:https://doi.org/10.1103/PhysRevB.63.134416
©2001 American Physical Society