Crystal growth, transport properties, and crystal structure of the single-crystal La_2-xBa_xCuO₄ (x=0.11)

We have attempted the crystal growth by the traveling-solvent floating-zone (TSFZ) method of La_2-xBa_xCuO₄ (x∼1/8), where the superconductivity is strongly suppressed. Under flowing O₂ gas at high pressure (4 bars), we have succeeded in growing single crystals for x=0.11 of 5 mm in diameter and 20 mm in length. Both in-plane and out-of-plane electrical resistivities of single-crystal La_2-xBa_xCuO₄ (x=0.11) exhibit a clear jump at ∼53 K. The temperature corresponds to the structural phase transition temperature between the orthorhombic midtemperature and tetragonal low-temperature phases, T_d2. Both in-plane thermoelectric power and Hall coefficient drop rapidly at T_d2 and decrease below T_d2 with decreasing temperature. These results are quite similar to those observed in single-crystal La_1.6-xNd_0.4Sr_xCuO₄ (x∼1/8), suggesting that the so-called static stripe order of holes and spins in the CuO₂ plane is formed below T_d2 in La_2-xBa_xCuO₄ (x∼1/8) as well as in La_1.6-xNd_0.4Sr_xCuO₄ (x∼1/8).