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arXiv · 0901.1331

Collective spin excitations in a quantum spin ladder probed by high-resolution Resonant Inelastic X-ray Scattering

J. Schlappa·T. Schmitt·F. Vernay·V. N. Strocov·V. Ilakovac·B. Thielemann·H. M. Rønnow·S. Vanishri·A. Piazzalunga·X. Wang·L. Braicovich·G. Ghiringhelli·C. Marin·J. Mesot·B. Delley·L. Patthey
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Abstract

We investigate magnetic excitations in the spin-ladder compound Sr$_{14}$Cu$_{24}$O$_{41}$ using high-resolution Cu $L_3$-edge Resonant Inelastic X-ray Scattering (RIXS). Our findings demonstrate that RIXS couples to collective spin excitations from a quantum spin-liquid ground state. In contrast to Inelastic Neutron Scattering (INS), the RIXS cross section changes only moderately over the entire Brillouin Zone (BZ), revealing a high sensitivity also at small momentum transfers. The two-triplon energy gap is found to be $100\pm 30$ meV. Our results are supported by calculations within an effective Hubbard model for a finite-size cluster.

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J. Schlappa, T. Schmitt, F. Vernay, V. N. Strocov, V. Ilakovac, B. Thielemann, H. M. Rønnow, S. Vanishri, A. Piazzalunga, X. Wang, L. Braicovich, G. Ghiringhelli, C. Marin, J. Mesot, B. Delley, L. Patthey. 2009-01-09. Collective spin excitations in a quantum spin ladder probed by high-resolution Resonant Inelastic X-ray Scattering. https://doi.org/10.1103/physrevlett.103.047401

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