Probing optically silent superfluid stripes in cuprates

Abstract

A nonlinear peek into stripes In many theoretical models of high-temperature superconductors, remnants of superconductivity persist to temperatures higher than the transition temperature, T C . Rajasekaran et al. used nonlinear terahertz spectroscopy to probe this region of the phase diagram of a cuprate superconductor that is well known for a stripe phase that appears for certain doping levels (see the Perspective by Ergeçen and Gedik). For a sample deep in the stripe phase, a large nonlinear signal persisted from the superconducting region up to temperatures much higher than T C . The findings suggest the formation of a peculiar spatially modulated superconducting state called the pair-density wave. Science , this issue p. 575 ; see also p. 519