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Chirality-spin separation in the Hubbard model on the kagome lattice

Effect of geometrical frustration in strongly-correlated metallic region is studied for the Hubbard model on the kagome lattice at half filling by a cluster extension of the dynamical mean-field theory combined with a continuous-time auxiliary-field quantum Monte Carlo method. We find that the electron correlation enhances the spin chirality in both vector and scalar channels. The chirality grows as decreasing temperature and exhibits a peak at a low temperature, indicating a new energy scale under strong correlation. The peak temperature is considerably lower than that for the local spin moment, namely, the characteristic temperatures for the chirality and the local moment are well separated. This is a signature of separation between spin and chiral degrees of freedom in the correlated metallic regime under geometrical frustration.