Magnetic dynamics of superconducting La1.86Sr0.14CuO4

Abstract

The general magnetic response function χ(Q,ω) of a superconducting (${\mathit{T}}_{\mathit{c}}$=33 K) single crystal of ${\mathrm{La}}_{1.86}$ ${\mathrm{Sr}}_{0.14}$ ${\mathrm{CuO}}_4$ is measured using inelastic neutron scattering. There is no gap in the magnetic fluctuation spectrum of the normal state. Superconductivity reduces χ’ ’(Q,ω) in progressively greater proportion as ħω decreases below 6 meV. The superconducting transition coincides with a sharp maximum in the temperature-dependent χ’ ’(Q,ω) for ħω=4 meV and Q fixed at the incommensurate wave vector characterizing the magnetic fluctuations in the normal state.