Measurement of magnetic excitations in the two-dimensional antiferromagnetic Sr₂CuO₂Cl₂ insulator using resonant x-ray scattering: evidence for extended interactions

M Guarise; B Dalla Piazza; M Moretti Sala; G Ghiringhelli; L Braicovich; H Berger; J N Hancock; D van der Marel; T Schmitt; V N Strocov; L J P Ament; J van den Brink; P-H Lin; P Xu; H M Rønnow; M Grioni

doi:10.1103/PhysRevLett.105.157006

Measurement of magnetic excitations in the two-dimensional antiferromagnetic Sr₂CuO₂Cl₂ insulator using resonant x-ray scattering: evidence for extended interactions

Phys Rev Lett. 2010 Oct 8;105(15):157006. doi: 10.1103/PhysRevLett.105.157006. Epub 2010 Oct 8.

Authors

M Guarise¹, B Dalla Piazza, M Moretti Sala, G Ghiringhelli, L Braicovich, H Berger, J N Hancock, D van der Marel, T Schmitt, V N Strocov, L J P Ament, J van den Brink, P-H Lin, P Xu, H M Rønnow, M Grioni

Affiliation

¹ Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Switzerland.

PMID: 21230933
DOI: 10.1103/PhysRevLett.105.157006

Abstract

We measured the momentum dependence of magnetic excitations in the model spin-1/2 2D antiferromagnetic insulator Sr2CuO2Cl2 (SCOC). We identify a single-spin-wave feature and a multimagnon continuum, with different polarization dependences. The spin waves display a large (70 meV) dispersion between the zone-boundary points (π, 0) and (π/2, π/2). Employing an extended t-t'-t''-U one-band Hubbard model, we find significant electronic hopping beyond nearest-neighbor Cu ions, indicative of extended magnetic interactions. The spectral line shape at (π, 0) indicates sizable quantum effects in SCOC and probably more generally in the cuprates.