Search for the existence of circulating currents in high-$T_c$ superconductors using the polarized neutron scattering technique

TL;DR

This paper reviews experimental efforts using polarized neutron scattering to detect circulating current order in high-$T_c$ superconductors, highlighting recent results that support Varma's circulating current theory.

Contribution

It provides a comprehensive review of experimental evidence for circulating currents in high-$T_c$ superconductors, emphasizing recent findings consistent with theoretical predictions.

Findings

Detection of magnetic signals consistent with circulating currents

Support for Varma's circulating current theory

Experimental evidence of long-range ordered current loops

Abstract

We review experimental attempts using polarized neutron scattering technique to reveal the existence in high temperature superconductors of a long-range ordered state characterized by the spontaneous appearance of current loops. We draw a particular attention to our recent results (B. Fauqu\'e {\it et al.}, {\it Phys. Rev. Lett.} {\bf 96}, 197001 (2006)) that, up to now, can be explained only by the theory of circulating current proposed by C.M. Varma.