Superconductivity and antiferromagnetism in the two-dimensional Hubbard model: a variational study

David Eichenberger, University of Fribourg

Abstract: A variational ground state of the repulsive Hubbard model on a square lattice is investigated numerically for an intermediate coupling strength (U = 8t) and for moderate sizes (from 6 x 6 to 10 x 10). Our ansatz is clearly superior to other widely used variational wave functions. The results for order parameters and correlation functions provide new insight for the antiferromagnetic state at half filling as well as strong evidence for a superconducting phase away from half filling. I will also comment on the relevance of our findings for layered cuprates.