Possible Josephson-like behavior of the YBa2Cu3O7-x single crystal twin   boundaries in low magnetic fields
  The experimental results on the magnetic response of YBCO single crystals with unidirectional twin boundary planes in low magnetic fields (0.01 - 1 Oe) are discussed. The observed non-monotone temperature dependence of magnetization is interpreted within a plausible model of a system of the Josephson weak links in the twin boundary planes and on the basis of the order parameter anisotropy. 
V.P. Timofeev, A.V. Bondarenko