Polar Kerr effect from chiral-nematic charge order

Yuxuan Wang, Andrey Chubukov, Rahul Nandkishore

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Abstract

We analyze the polar Kerr effect in an itinerant electron system on a square lattice in the presence of a composite charge order proposed for the pseudogap state in underdoped cuprates. This composite charge order preserves discrete translational symmetries, and is "chiral nematic" in the sense that it breaks time-reversal symmetry, mirror symmetries in x and y directions, and C4 lattice rotation symmetry. The Kerr angle θK in C4-symmetric system is proportional to the antisymmetric component of the anomalous Hall conductivity σxy-σyx. We show that this result holds when C4 symmetry is broken. We show that in order for σxy and σyx to be nonzero the mirror symmetries in x and y directions have to be broken, and that for σxy-σyx to be nonzero time-reversal symmetry has to be broken. The chiral-nematic charge order satisfies all these conditions, such that a nonzero signal in a polar Kerr effect experiment is symmetry allowed. We further show that to get a nonzero θK in a one-band spin-fluctuation scenario, in the absence of disorder, one has to extend the spin-mediated interaction to momenta away from (π,π) and has to include particle-hole asymmetry. Alternatively, in the presence of disorder, one can get a nonzero θK from impurity scattering: either due to skew scattering (with non-Gaussian disorder) or due to particle-hole asymmetry in case of Gaussian disorder. The impurity analysis in our case is similar to that in earlier works on Kerr effect in px+ipy superconductors, however, in our case, the magnitude of θK is enhanced by the flattening of the Fermi surface in the "hot" regions, which mostly contribute to charge order.

Original languageEnglish (US)
Article number205130
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume90
Issue number20
DOIs
StatePublished - Nov 20 2014

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