Effect of vortex fluctuations on ²⁰⁵Tl spin-lattice relaxation in the mixed state of Tl₂Ba₂CuO₆.

  Abstract:
 The spin-lattice relaxation rate W on ²⁰⁵Tl has been measured in the mixed state of a Tl₂Ba₂CuO₆ aligned powder sample with T_c=100 K. At T < 25 K, W µ T and decreases with increasing magnetic field. This behavior is explained as caused by fluctuations of pancake vortices; the latter induce a time dependent random magnetic field which causes the relaxation of nuclear spins.