Internal structure of the singletdx2−y2hole pair in an antiferromagnet

Abstract

Exact diagonalizations of two-dimensional $t-J$ clusters reveal dominant hole-hole correlations at distance √2 (i.e., between holes on next-nearest-neighbor sites). A singlet $d_{x^2-y^2}$ pair operator is proposed to account for the spatial extension of the two-hole-bound pair beyond nearest-neighbor sites.