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Quasi-two-dimensional Bose-Einstein condensation of spin triplets in dimerized quantum magnet Ba$_2$CuSi$_2$O$_6$Cl$_2$
- Source :
- Phys. Rev. B 94, 094421 (2016)
- Publication Year :
- 2016
-
Abstract
- We synthesized single crystals of composition Ba$_2$CuSi$_2$O$_6$Cl$_2$ and investigated its quantum magnetic properties. The crystal structure is closely related to that of the quasi-two-dimensional (2D) dimerized magnet BaCuSi$_2$O$_6$ also known as Han purple. Ba$_2$CuSi$_2$O$_6$Cl$_2$ has a singlet ground state with an excitation gap of ${\Delta}/k_{\rm B}\,{=}\,20.8$ K. The magnetization curves for two different field directions almost perfectly coincide when normalized by the $g$-factor except for a small jump anomaly for a magnetic field perpendicular to the $c$ axis. The magnetization curve with a nonlinear slope above the critical field is in excellent agreement with exact-diagonalization calculations based on a 2D coupled spin-dimer model. Individual exchange constants are also evaluated using density functional theory (DFT). The DFT results demonstrate a 2D exchange network and weak frustration between interdimer exchange interactions, supported by weak spin-lattice coupling implied from our magnetostriction data. The magnetic-field-induced spin ordering in Ba$_2$CuSi$_2$O$_6$Cl$_2$ is described as the quasi-2D Bose-Einstein condensation of triplets.<br />Comment: 9 pages, 7 figures, to appear in Phys. Rev. B
- Subjects :
- Condensed Matter - Strongly Correlated Electrons
Subjects
Details
- Database :
- arXiv
- Journal :
- Phys. Rev. B 94, 094421 (2016)
- Publication Type :
- Report
- Accession number :
- edsarx.1609.00438
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1103/PhysRevB.94.094421