Low-Temperature Thermodynamics of Spin-1/2 Orthogonal-Dimer Chain with Ising and Heisenberg Interactions |
| T. Verkholyaka,b, J. Strečkab
aInstitute for Condensed Matter Physics, NAS of Ukraine, 1 Svientsitskii Street, 79011 L'viv, Ukraine bInstitute of Physics, Faculty of Sciences, P. J. Safarik University, Park Angelinum 9, 041 54 Košice, Slovakia |
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| We consider an exactly solvable version: of the quantum spin-1/2 orthogonal-dimer chain with the Heisenberg intra-dimer and Ising inter-dimer couplings. The investigated quantum spin system exhibits at zero temperature fractional plateaux at 1/4 and 1/2 of the saturation magnetization and it has a highly degenerate ground state at critical fields where the magnetization jumps. We study the field dependence of the specific heat at low temperature. The lattice-gas description is formulated in a vicinity of critical fields to explain the low-temperature behaviour of specific heat. |
DOI: 10.12693/APhysPolA.126.22 PACS numbers: 75.10.Jm, 75.10.Pq, 75.30.Gw, 75.40.Cx |