Abstract
We followed the Shastry-Shraiman formulation of Raman scattering in Hubbard systems and considered the Raman intensity profile in the spin- “perfect” kagome lattice herbertsmithite , assuming the ground state is well-described by the U(1) Dirac spin-liquid state. In the derivation of the Raman matrix, we found that the spin-chirality term appears in the channel in the kagome lattice at the order, but (contrary to the claims by Shastry and Shraiman) vanishes in the square lattice to that order. In the ensuing calculations on the spin- kagome lattice, we found that the Raman intensity profile in the channel is invariant under an arbitrary rotation in the kagome plane, and that in all (, , and ) symmetry channels the Raman intensity profile contains broad continua that display power-law behaviors at low energy, with exponent approximately equal to 1 in the channel and exponent approximately equal to 3 in the and the channels. For the channel, the Raman profile also contains a characteristic singularity, which arose in our model from an excitation of the emergent U(1) gauge field.
12 More- Received 4 November 2009
DOI:https://doi.org/10.1103/PhysRevB.81.024414
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