Time relaxation of flux rotation and dimensional crossover in La1.85Sr0.15CuO4

Vector magnetization measurements in La1.85Sr0.15CuO4 under a steady field H tilted relative to the ab plane show that the induction B rotates toward H with time. The rate of rotation as a function of temperature exhibits two peaks separated by a dip around 12 K. Measurements of the remnant induction show that for temperatures below similar to 12 K, B rotates towards the c axis, whereas for temperatures above similar to 12 K, B rotates towards the ab planes. We argue that these data are consistent with a two-dimensional and a three-dimensional behavior below and above the dimensional crossover temperature, similar to 12 K, respectively.