Observing the fluctuating stripes in high-T_c superconductors

¹  Instituut Lorentz voor de theoretische natuurkunde, Universiteit Leiden - P.O. Box 9506, 2300 RA Leiden, The Netherlands
²  Department of Physics, Washington University - St. Louis, MO 63160, USA
³  Theoretical Physics Department, Moscow Institute of Steel & Alloys - 119991 Moscow, Russia

Received: 21 June 2007
Accepted: 7 November 2007

Abstract

Superfluids and superconductors have been around for a long time and their explanation in terms of the Bogoliubov theory for bosons and the BCS theory for fermions belong to the highlights of twentieth century physics. However, it appears that these theories are too primitive to address the high-T_c superconductivity found in copper oxides. These electron systems seem to behave more like a dense, strongly correlated liquid contrasting markedly with the conventional quantum gasses: these show strong dynamical correlations on mesoscopic length and time scales associated with stripes, a particular form of electron crystallization. Resting on the gauge theory of topological quantum melting in 2+1 dimensions relevant for the cuprates, we describe the limit which is exactly opposite to the gas limit: the superconductor with the maximum possible amount of transient translational order. We predict that in this “orderly limit” an extra collective mode appears, and this “massive shear photon” can be regarded as a universal fingerprint of the fluctuating stripes. This mode is visible in the electrodynamic response and the ramification of our theory is that electron energy loss spectroscopy can be employed to prove or disprove the existence of dynamical stripes in cuprate superconductors.