Triplet excitations in the frustrated spin ladder Li$_2$Cu$_2$O(SO$_4$)$_2$

Ornella Vaccarelli; Andreas Honecker; Paola Giura; Keevin Béneut; Björn Fåk; Gwenaëlle Rousse; Guillaume Radtke

doi:10.1103/PhysRevB.99.064416

paper

Triplet excitations in the frustrated spin ladder Li $_{2}$ Cu $_{2}$ O(SO $_{4}$ ) $_{2}$

arXiv:1902.02798 · doi:10.1103/PhysRevB.99.064416

Abstract

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 $Δ = 10.6$ 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.

to appear in Phys. Rev. B, 10 pages including 7 figure (supplemental series provided as ancillary files)

Triplet excitations in the frustrated spin ladder Li2​Cu2​O(SO4​)2​

Abstract

References in corpus (5)

Triplet excitations in the frustrated spin ladder Li $_{2}$ Cu $_{2}$ O(SO $_{4}$ ) $_{2}$