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Cumulant approach to weakly doped antiferromagnets

Matthias Vojta·Klaus W. Becker
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Abstract

We present a new approach to static and dynamical properties of holes and spins in weakly doped antiferromagnets in two dimensions. The calculations are based on a recently introduced cumulant approach to ground--state properties of correlated electronic systems. The present method allows to evaluate hole and spin--wave dispersion relations by considering hole or spin excitations of the ground state. Usually, these dispersions are found from time--dependent correlation functions. To demonstrate the ability of the approach we first derive the dispersion relation for the lowest single hole excitation at half--filling. However, the main purpose of this paper is to focus on the mutual influence of mobile holes and spin waves in the weakly doped system. It is shown that low-energy spin excitations strongly admix to the ground--state. The coupling of spin waves and holes leads to a strong suppression of the staggered magnetization which can not be explained by a simple rigid--band picture for the hole quasiparticles. Also the experimentally observed doping dependence of the spin--wave excitation energies can be understood within our formalism.

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Matthias Vojta, Klaus W. Becker. 1996-09-11. Cumulant approach to weakly doped antiferromagnets. https://doi.org/10.1103/physrevb.54.15483

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