Time-reversal symmetry breaking by a (d+id) density-wave state in underdoped cuprate superconductors

Phys Rev Lett. 2008 May 30;100(21):217004. doi: 10.1103/PhysRevLett.100.217004. Epub 2008 May 30.

Abstract

It was proposed that the id(x(2)-y(2)) density-wave state (DDW) may be responsible for the pseudogap behavior in the underdoped cuprates. Here we show that the admixture of a small d(xy) component to the DDW state breaks the symmetry between the counterpropagating orbital currents of the DDW state and, thus, violates the macroscopic time-reversal symmetry. This symmetry breaking results in a nonzero polar Kerr effect, which has recently been observed in the pseudogap phase.