Magnetic Quantum Critical Point in YBa_2Cu_3O_{7-delta}? Resolving the Correlation Length Controversy

Abstract

A mode coupling calculation which previously explained the Mott gap collapse induced in cuprates by electron doping is applied to the analogous problem of hole doping. A plateau in the q-space susceptibility is found to inhibit the rate of susceptibility divergence as T goes to 0. This effect could reconcile neutron and NMR measurements of the correlation length in this regime, and clarify the issue of proximity to a quantum critical point.