Schematic image of the incommensurate smectic modulations in the cuprate pseudogap states (top) showing a dislocation. At the site of the dislocation, a 2 π topological defect in the spatial phase of the smectic exists (middle). A characteristic fluctuation of the intra-unit-cell breaking of C4-symmetry is observed independently at every such topological defect (bottom), leading to a Ginzburg-Landau representation of the interaction between these two distinct broken symmetry states.

A. Mesaros, K. Fujita, H. Eisaki, S. Uchida, J. C. Davis, S. Sachdev, J. Zaanen, M. J. Lawler, E. – A. Kim Science 333, 426 (2011).

Image courtesy: Dr. K. Fujita and Prof. J. C. Davis, Cornell University.