Anomalous behavior of the interlayer resistance of a BSCCO-2212 crystal in a parallel magnetic field

The electrical resistance across the Cu-O layers of a BSCCO-2212 single crystal is investigated in the range of angles 0 degrees less than or equal to phi less than or equal to 90 degrees between the magnetic field H less than or equal to 15 T and the ab plane, It is found that the temperature dependence R(T) at the transition into the mixed state is much sharper for phi similar or equal to 0 degrees than for 1 degrees less than or similar to phi less than or similar to 90 degrees, where R is determined by the perpendicular component of the magnetic field and is described by the Arrhenius law R similar to exp(-U/T). For H parallel to ab hysteretic jumps in R(T,H), which vanish as the current increases, are observed at fields in the range 5.5 less than or equal to H less than or equal to 11 T. This effect can be attributed to a commensurate phase transition in a lattice of Josephson vortices.