Parton theory of magnetic polarons: Mesonic resonances and signatures in dynamics. (arXiv:1712.01874v1 [cond-mat.quant-gas])

When a mobile hole is moving in an anti-ferromagnet it distorts the
surrounding Neel order and forms a magnetic polaron. Such interplay between
hole motion and anti-ferromagnetism is believed to be at the heart of high-Tc
superconductivity in cuprates. We study a single hole described by the t-Jz
model with Ising interactions between the spins in 2D. This situation can be
experimentally realized in quantum gas microscopes. When the hole hopping is
much larger than couplings between the spins, we find strong evidence that
magnetic polarons can be understood as bound states of two partons, a spinon
and a holon carrying spin and charge quantum numbers respectively. We introduce
a microscopic parton description which is benchmarked by comparison with
results from advanced numerical simulations. Using this parton theory, we
predict a series of excited states that are invisible in the spectral function
and correspond to rotational excitations of the spinon-holon pair. This is
reminiscent of mesonic resonances observed in high-energy physics, which can be
understood as rotating quark antiquark pairs. We also apply the strong coupling
parton theory to study far-from equilibrium dynamics of magnetic polarons
observable in current experiments with ultracold atoms. Our work supports
earlier ideas that partons in a confining phase of matter represent a useful
paradigm in condensed-matter physics and in the context of high-Tc
superconductivity. While direct observations of spinons and holons in real
space are impossible in traditional solid-state experiments, quantum gas
microscopes provide a new experimental toolbox. We show that, using this
platform, direct observations of partons in and out-of equilibrium are
possible. Extensions of our approach to the t-J model are also discussed. Our
predictions in this case are relevant to current experiments with quantum gas
microscopes for ultracold atoms.

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