We investigate magnetic excitations in the spin-ladder compound Sr14Cu24O41 using high-resolution Cu L3-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±30 meV. Our results are supported by calculations within an effective Hubbard model for a finite-size cluster.
@article{arxiv.0901.1331,
title = {Collective spin excitations in a quantum spin ladder probed by high-resolution Resonant Inelastic X-ray Scattering},
author = {J. Schlappa and T. Schmitt and F. Vernay and V. N. Strocov and V. Ilakovac and B. Thielemann and H. M. Rønnow and S. Vanishri and A. Piazzalunga and X. Wang and L. Braicovich and G. Ghiringhelli and C. Marin and J. Mesot and B. Delley and L. Patthey},
journal= {arXiv preprint arXiv:0901.1331},
year = {2019}
}