2005/09/30 by H. Tsujii, B. Andraka, M. Uchida +3 · 1 citation
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Magnetic and transport properties of perovskites and related materials #Physics of Superconductivity and Magnetism #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.72.214434
published as Phys. Rev. B 72, 214434 (2005) · 6 pages, 5 figures, revised version
arxiv created 2005/11/04 · openalex publication_date 2005/12/28 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We have measured the specific heat of the coupled spin-dimer antiferromagnet Ba3Mn2O8 to 50\phantom\rule0.3em0exmK in temperature and to 29\phantom\rule0.3em0exT in the magnetic field. The experiment extends to the midpoint of the field region (25.9\phantom\rule0.3em0exT\ensuremath\leqslantH\ensuremath\leqslant32.3\phantom\rule0.3em0exT) of the magnetization plateau at 1∕2 of the saturation magnetization, and reveals the presence of three ordered phases in the field region between that of the magnetization plateau and the low-field spin-liquid region. The exponent of the phase boundary with the thermally disordered region is smaller than the theoretical value based on the Bose-Einstein condensation of spin triplets. At zero field and 29\phantom\rule0.3em0exT, the specific-heat data show gapped behaviors characteristic of spin liquids. The zero-field data indicate that the gapped triplet excitations form two levels whose energies differ by nearly a factor of 2. At least the lower level is well localized. The data at 29\phantom\rule0.3em0exT reveal that the low-lying excitations at the magnetization plateau are weakly delocalized.