Emergent dimensional reduction of the spin sector in a model for narrow-band manganites

The widely used Double-Exchange model for manganites is shown to support various "striped" phases at filling fractions 1/n (n=3, 4, 5...), in the previously unexplored regime of narrow bandwidth and small Jahn-Teller coupling. Working in two dimensions, our main result is that these stripes can be individually spin flipped without a physically relevant change in the energy, i.e., we find a large groundstate manifold with nearly degenerate energies. The two-dimensional spin system thus displays an unexpected dynamically generated dimensional reduction into decoupled one-dimensional stripes, even though the electronic states remain two-dimensional. Relations of our results with recent literature addressing compass models in quantum computing are discussed.