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Two-particle (2-p) excitations such as spin and charge excitations play a key role in high-Tc cuprate superconductors (HTSC). On the basis of a parameter-free theory, which extends the Variational Cluster Approach (a recently developed embedded cluster method) to 2-p excitations, the magnetic excitations of HTSC are shown to be reproduced for a Hubbard model within the relevant strong-coupling regime [1]. In particular, the resonance mode in the underdoped regime, its intensity, "hour-glass" dispersion and doping dependence are in good overall agreement with experiments [1]. Combined with the earlier results for the phase diagram and one-particle excitations, such as the electronhole asymmetry in the doping dependence of AF and SC phases [2] and the presence of a gap dichotomy of the nodal and antinodal SC gaps [3], a consistent picture emerges, which lends substantial support to Hubbard-model descriptions of high-Tc cuprate superconductivity. [1] S. Brehm et al., arXiv:0811.0552. [2] M. Aichhorn et al., Phys. Rev. B 75, 235117 (2006). [3] M. Aichhorn et al., Phys. Rev. Lett. 99, 257002 (2007). |
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