Hole dispersion and symmetry of the superconducting order parameter for underdopedCuO2bilayers and the three-dimensional antiferromagnets

Abstract

We calculate the dispersion of a hole in CuO 2 bilayers and three-dimensional ͑3D͒ 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 d x 2 Ϫy 2 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 d 3z 2 Ϫr 2 and s x 2 ϩy 2 ϩz 2. For an isotropic 3D antiferromagnet the d x 2 Ϫy 2 and d 3z 2 Ϫr 2 channels are degenerate. Our results are compared with other predictions in the literature.

Angle-resolved photoemission spectral function in lightly doped and antiferromagnetically ordered YBa2Cu3O6+Chen1, Sushkov2, Tohyama3 2011Phys. Rev. B121160View full textAdd to dashboardCite

“…The similar result for undoped YBCO was previously obtained in Ref. 6. The antiferromagnetic correlations are due to the antiferromegnetic exchange J ⊥ ≈ 10 meV between the layers.…”

“…[1][2][3][4][5][6][7] This implies that the method is justified at t/J > 1. A very important point is that due to the spin structure of the theory (conservation of S z ) there is no singleloop correction to the hole-magnon vertex shown in Fig.…”

“…[1][2][3][4][5][6][7] The Green's function (16) has the parity index ± reflecting the double-layer structure and the pseudospin index σ =↑↓ reflecting the AF structure. Since the up and down pseudospins are degenerate, we omit the psedospin index σ for the rest of the article, although one should keep in mind that vertexes in Eq.…”

“…6 This implies that at the MBZ boundary, the magnon dispersion of either parity are degenerate, and the hole …”

“…SCBA has been widely applied to study a single hole dressed by spin fluctuations. [1][2][3][4][5][6][7] On the other hand, application of the method at finite doping has been limited 30-33 because usually even a tiny doping destroys the long-range AF order. The point is that SCBA can be parametrically justified only in the presence of the AF order because the order guaranties that the single-loop vertex correction is forbidden (the "Migdal theorem"), and hence the method is accurate up to double-loop vertex corrections.…”