title: Lack of evidence for orbital-current effects in the high-temperature Y2Ba4Cu7O15-delta superconductor using 89Y nuclear magnetic resonance.
abstract: We have performed NMR measurements at the Y site on a c-axis-oriented powder sample of the cuprate superconductor Y2Ba4Cu7O15-delta to search for the possible orbital-current phase. The temperature dependence of the Y linewidth and relaxation behavior in the normal-conducting phase were studied down to 100 K. These measurements give upper limits for a static magnetic field and the amplitude of a fluctuating magnetic field at the Y site of < or approximately 0.15 and < or approximately 0.7 mT, respectively. These values provide significant constraints on possible static or quasistatic orbital currents.
authors.affiliation: Physik-Institut, Universität Zürich, CH-8057 Zürich, Switzerland. simon.straessle@physik.uzh.ch
authors.forename: S
authors.initials: S
authors.lastname: Strässle
authors.forename: J
authors.initials: J
authors.lastname: Roos
authors.forename: M
authors.initials: M
authors.lastname: Mali
authors.forename: H
authors.initials: H
authors.lastname: Keller
authors.forename: T
authors.initials: T
authors.lastname: Ohno