Résumé : Since tetragonal CuO (t-CuO) is composed of well separated 2D CuO planes [1] it appears as an ideal candidate to connect model calculations with real materials in the quest of understanding the nature of high-temperature superconductivity. We investigate the low-energy electronic properties of t-CuO by means of Cellular Dynamical Mean Field Theory [2, 3] using a 2D Hubbard model. From experiment it was proposed that single layers of t-CuO can be viewed as two weakly interconnected sublattices [4, 5]. Our calculations support this assumption: we find a suppression of the nearest-neighbor (NN) correlations for the benefit of the next-NN ones. The calculated spectral function is in remarkable agreement with photoemission experiments [5], showing that a one-band model is sufficient to capture the low-energy physics of t-CuO. We study the transition from paramagnetic to antiferromagnetic phase at finite temperature and elucidate the nature of the insulating regime in both phases. Finally, we predict that upon hole-doping the sublattice decoupling translates into a superconductivity order parameter of unusual symmetry, which moreover coexist with antiferromagnetic stripes.
1. W. Siemons et al, PRB 79(19):195122, 2009
2. G. Kotliar et al, PRL 97:186401, 2001
3. T. Maier et al, Rev. Mod. Phys. 87:186401, 2005
