Internal static electric and magnetic field at the copper cite in a single crystal of the electron-doped high-T$_{c}$ superconductor Pr$_{1.85}$Ce$_{0.15}$CuO$_{4-y}$

Guoqing Wu; F. Zamborszky; A. P. Reyes; P. L. Kuhns; R. L. Greene; W. G. Clark

doi:10.1103/PhysRevB.90.214506

paper

Internal static electric and magnetic field at the copper cite in a single crystal of the electron-doped high-T $_{c}$ superconductor Pr $_{1.85}$ Ce $_{0.15}$ CuO $_{4 - y}$

arXiv:1410.1696 · doi:10.1103/PhysRevB.90.214506

Abstract

We report $^{63, 65}$ Cu-NMR spectroscopy and Knight shift measurements on a single crystal of the electron-doped high- $T_{c}$ superconductor Pr $_{1.85}$ Ce $_{0.15}$ CuO $_{4 - y}$ (PCCO) with an applied magnetic field ( $H$ ) up to 26.42 T. A very small NQR frequency is obtained with the observation of the spectrum, which shows an extremely wide continuous distribution of it that becomes significant narrower below 20 K at $H$ $∥$ $c$ where the superconductivity is completely suppressed, indicating a significant change in the charge distribution at the Cu site, while the corresponding changes at $H$ $⊥$ $c$ is negligible when the superconductivity is present or not fully suppressed. The Knight shift and central linewidth are proportional to the applied magnetic field with a high anisotropy. We find that the magnitude of the internal static magnetic field at the copper is dominated by the anisotropic Cu $^{2 +}$ 3 $d$ -orbital contributions, while its weak temperature-dependence is mainly determined by the isotropic contact hyperfine coupling to the paramagnetic Pr $^{3 +}$ spins, which also gives rise to the full distribution of the internal static magnetic field at the copper for $H$ $⊥$ $c$ . This internal static electric and magnetic field environment at the copper is very different from that in the hole-doped cuprates, and may provide new insight into the understanding of high- $T_{c}$ superconductivity. Other experimental techniques are needed to verify whether the observed significant narrowing of the charge distribution at the Cu site with $H$ $∥$ $c$ is caused by the charge ordering (CO) [E. H. da Silva Neto $e t a l .$ , to be published in Science] \cite{ehdsn} or a new type of charge modulation.

8 pages, 6 figures, submitted to Phys. Rev. B

Internal static electric and magnetic field at the copper cite in a single crystal of the electron-doped high-Tc​ superconductor Pr1.85​Ce0.15​CuO4−y​

Abstract

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Internal static electric and magnetic field at the copper cite in a single crystal of the electron-doped high-T $_{c}$ superconductor Pr $_{1.85}$ Ce $_{0.15}$ CuO $_{4 - y}$