Inhomogeneous electronic structure probed by spin-echo experiments in the electron doped high-Tc superconductor Pr_{1.85}Ce_{0.15}CuO_{4-y}

TL;DR

This study uses 63Cu NMR spin-echo decay measurements to reveal an inhomogeneous electronic structure in the electron-doped high-Tc superconductor Pr_{1.85}Ce_{0.15}CuO_{4-y}, showing temperature-dependent and rf pulse-sensitive behavior.

Contribution

It provides evidence for a static inhomogeneous electronic structure in PCCO, demonstrated through spin-echo decay rate dependence on temperature and rf pulse parameters.

Findings

Spin-echo decay rate varies with temperature below 55K.

Decay rate depends on rf pulse parameters below 25K.

Evidence for static inhomogeneous electronic structure in PCCO.

Abstract

63Cu nuclear magnetic resonance (NMR) spin-echo decay rate (T_2^{-1}) measurements are reported for the normal and superconducting states of a single crystal of Pr_{1.85}Ce_{0.15}CuO_{4-y} (PCCO) in a magnetic field B_0=9T over the temperature range 2K<T<200K. The spin-echo decay rate is temperature-dependent for T<55K, and has a substantial dependence on the radio frequency (rf) pulse parameters below T~25K. This dependence indicates that T_2^{-1} 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.