Triplet excitations in the frustrated spin ladder Li$_2$Cu$_2$O(SO$_4$)$_2$
| Autor: | Vaccarelli, Ornella, Honecker, Andreas, Giura, Paola, Béneut, Keevin, Fåk, Björn, Rousse, Gwenaëlle, Radtke, Guillaume |
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| Rok vydání: | 2019 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 99, 064416 (2019) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.99.064416 |
| Popis: | Magnetic excitations of the recently discovered frustrated spin-1/2 two-leg ladder system Li$_2$Cu$_2$O(SO$_4$)$_2$ are investigated using inelastic neutron scattering, magnetic susceptibility and infrared absorption measurements. Despite the presence of a magnetic dimerization concomitant with the tetragonal-to-triclinic structural distortion occurring below 125 K, neutron scattering experiments reveal the presence of dispersive triplet excitations above a spin gap of $\Delta = 10.6$ meV at 1.5 K, a value consistent with the estimates extracted from magnetic susceptibility. The likely detection of these spin excitations in infrared spectroscopy is explained by invoking a dynamic Dzyaloshinskii-Moriya mechanism in which light is coupled to the dimer singlet-to-triplet transition through an optical phonon. These results are qualitatively explained by exact diagonalization and higher-order perturbation calculations carried out on the basis of the dimerized spin Hamiltonian derived from first-principles. Comment: to appear in Phys. Rev. B, 10 pages including 7 figure (supplemental series provided as ancillary files) |
| Databáze: | arXiv |
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