Resonant inelastic X-ray scattering study of spin-wave excitations in the cuprate parent compound Ca 2 CuO 2 Cl 2
Résumé
Resonant inelastic x-ray scattering was performed at the Cu L3 edge on the undoped cuprate Ca2CuO2Cl2. The spin wave dispersion along 100 and 110 was measured, yielding an estimate of the superexchange parameter J = 160 ± 10 meV using a classical spin-1/2 2D Heisenberg model with nearest-neighbor interactions, or J = 135 ± 9 meV including quantum fluctuations. The 45 meV dispersion along the zone boundary points (0.5, 0) and (0.25, 0.25) implies that next-nearest neighbor interactions in this compound are intermediate between the values in La2CuO4 and Sr2CuO2Cl2. Comparison of our measurement of the spin superexchange parameter with quantum many-body calculations are easier, since Ca2CuO2Cl2 is composed of only low Z atoms, and will help improve our understanding of the role of magnetic excitations and correlations in the cuprates.
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