Hole dispersion and symmetry of the superconducting order parameter for underdoped CuO2 bilayers and the three-dimensional antiferromagnets

Abstract

We calculate the dispersion of a hole in CuO2 bilayers and three-dimensional (3D) antiferromagnets, using the self-consistent Born approximation to the t-J model. Superconductivity and the symmetry of its order parameter are studied introducing a nearest-neighbor density-density attraction induced by short range antiferromagnetic fluctuations, as described in recent studies for the single layer cuprates. The well-known pairing in the dx2−y2 channel observed for one plane remains robust when three-dimensional interactions are turned on. In bilayers, as the exchange along the direction perpendicular to the planes grows, eventually a transition to an ‘‘s-wave’’ state is observed with an order parameter mixture of d3z2−r2 and sx2+y2+z2. For an isotropic 3D antiferromagnet the dx2−y2 and d3z2−r2 channels are degenerate. Our results are compared with other predictions in the literature. © 1996 The American Physical Society.

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