Can the cuprate parent compounds superconduct? Insight from cluster
Mardi 18/03/2008, 11:00
Petit Amphi, LPS Bât. 510, Orsay
Recent STM experiments indicate (arXiv:0801.2772) a possibility of pressure tuned transition from antiferromagnetic insulator (AF) to metallic state in the parent compounds of high-Tc cuprates.
We study this possibility within the half-filled Hubbard model on frustrated square lattice, which is solved on a cluster using the Variational Cluster Approximation (VCA). Depending on the level of frustration (ratio of hoppings t'/t), we find two phases with long-range AF order as well as, notably, the d-wave superconducting (SC) phase which is favoured by frustration when Hubbard's U is not too large. Intriguingly, we also find a broad region of microscopic coexistence where both AF and SC order parameters have non-zero values. The physics of the metal-insulator transition in the normal state is also studied.
Reference: A. Nevidomskyy et al, PRB 2008 (in press), arXiv:0711.0214.