Temperature dependence of La spin-lattice relaxation time in the high-TcsuperconductorLa1.85Sr0.15CuO4

Abstract

We present NMR spin-lattice relaxation measurements of La, obtained at 32.9 MHz in the compound ${\mathrm{La}}_{1.85}$ ${\mathrm{Sr}}_{0.15}$Cu${\mathrm{O}}_4$ over the temperature range 12-300 K. Although conductivity and acsusceptibility measurements on a piece of the same pellet indicate an onset of the superconducting transition at 37 and 32 K, respectively, an anomaly in the spin-lattice relaxation rate is observed around $T=52\mathrm{}$ K, which can be attributed either to a weak structural phase transition or to precursory magnetic fluctuations. Below the superconducting transition down to 12 K, $T_1$ stays constant and equal to 530±10 ms.