Gap Anisotropy, Spin Fluctuations and Normal-State Properties of the Electron Doped Superconductor Sr0.9La0.1CuO2

Abstract

We report the results from a thermopower and a Cu nuclear magnetic resonance (NMR) study of the infinite CuO2 layer electron doped high temperature superconducting cuprate (HTSC), Sr0.9La0.1CuO2. We find that the temperature dependence of the thermopower, S(T), is different from that observed in the hole doped HTSC. In particular, we find that dS(T)/dT is positive above ~120 K. However, we show that S(T) can still be described by the same model developed for the hole doped HTSC and hence S(T) is not anomalous and does not imply phonon mediated pairing as has previously been suggested. The Cu NMR data reveal a Knight shift and spin lattice relaxation rate below Tc that are inconsistent with isotropic s-wave pairing. The Cu spin lattice relaxation rate in the normal state, however, is Curie-Weiss like and is comparable to that of the optimally and overdoped hole doped HTSC, La2-xSrxCuO4. The magnitude of the Knight shift indicates that the density of states at the Fermi level is anomalously small when compared with the hole doped HTSC with the same Tc, indicating that the size of the density of states at the Fermi level is of little importance in the HTSC. We find no evidence of the normal state pseudogap that is observed in the hole doped HTSC and which was recently reported to exist in the electron doped HTSC, Nd1.85Ce0.15CuO4, from infrared reflectance measurements.

21 pages, submitted to Phys. Rev. B. The manuscript was changed in repsonse to a conference presentation that we were not aware of (http://xxx.lanl.gov/abs/cond-mat/0112401). This version also includes thermopower data

References in corpus (6)

• Anomalous electronic structure and pseudogap effects in Nd_1.85Ce_0.15CuO_4
• Evidence for a Transition in the Pairing Symmetry of the Electron-Doped Cuprates La_{2-x}Ce_xCuO_{4-y} and Pr_{2-x}Ce_xCuO_{4-y}
• Strongly correlated s-wave pairing in the n-type infinite-layer cuprate
• Evidence for a Nodeless Gap from the Superfluid Density of Optimally Doped Pr_{1.855}Ce_{0.145}CuO_{4-y} Films
• Gapped tunneling spectra in the normal state of Pr${}_{2-x}$Ce${}_x$CuO${}_4$
• Superconductivity and Spin Fluctuations in the Electron-Doped Infinitely-Layered High Tc Superconductor Sr${}_0.9$La${}_0.1$CuO${}_2$ (Tc=42K)

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• Muon-Spin-Rotation Measurements of the Penetration Depth in the Infinite-Layer Electron-Doped Cuprate Superconductor Sr0.9La0.1CuO2
• Distribution of electrons and holes in cuprate superconductors as determined from ${}^{17}$O and ${}^{63}$Cu nuclear magnetic resonance
• Strongly Anisotropic s-Wave Gaps in Exotic Superconductors
• Uniform mixing of antiferromagnetism and high-T_c superconductivity in multilayered copper oxides Ba_2Ca_{n-1}Cu_nO_{2n}F_2 with apical fluorines (n=2,3,4): Cu-NMR/NQR and F-NMR
• Dimensionality of superconductivity in the infinite-layer high-temperature cuprate Sr0.9M0.1CuO2 (M = La, Gd)
• Phase-sensitive evidence for dx2-y2-pairing symmetry in the parent-structure high-Tc cuprate superconductor Sr1-xLaxCuO2
• Unconventional Low-Energy Excitations of Cuprate Superconductors
• Non-universal pairing symmetry and pseudogap phenomena in hole- and electron-doped cuprate superconductors
• First principles study of local electronic and magnetic properties in pure and electron-doped Nd${}_2$CuO${}_4$