Small-polaron theory of doped antiferromagnets

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Abstract
The spin-hole coherent-state path integral is used to generate a systematic large-spin expansion of the t-J model on the square lattice. The single hole’s classical energy is minimized by small polarons with short-ranged interactions. Intersublattice hopping of polarons is forbidden by a tunneling selection rule. We derive the low-energy Lagrangian which reduces to the model of Wiegmann, Wen, Shankar, and Lee of Néel-gauge-field induced superconductivity.