Inhomogeneous Electronic Structure Probed by Spin-Echo Experiments in the Electron Doped High-TcSuperconductorPr1.85Ce0.15CuO4−y

Abstract

63Cu nuclear magnetic resonance spin-echo decay rate (T-12) measurements are reported for the normal and superconducting states of a single crystal of Pr(1.85)Ce(0.15)CuO(4-y) in a magnetic field B(0)=9 T over the temperature range 2<T<200 K. The spin-echo decay rate is temperature dependent for T<55 K and has a substantial dependence on the radio frequency (rf) pulse parameters below T approximately 25 K. This dependence indicates that T-12 is strongly effected by a local magnetic field distribution that can be modified by the rf pulses, including ones that are not at the nuclear Larmor frequency. The low-temperature results are consistent with the formation of a static inhomogeneous electronic structure that couples to the rf fields of the pulses.