Periodic negative magnetoresistance in granular YBa2Cu3O7-delta nanowires

Magneto-transport measurements in YBa2Cu3O7-delta nanowires, comprising a single layer of a small number of grains, reveal periodic magnetoresistance oscillations in a wide temperature range below the transition. The rich structure of these oscillations manifests a negative magnetoresistance in the initial part of each cycle beginning at zero magnetic field. The salient features of these unique oscillations indicate the presence of pi Josephson junctions in the granular wires, arising from the d-wave pairing symmetry in YBa2Cu3O7-delta. Copyright (C) EPLA, 2013