Growth and Superconductive Properties of La2CuO4 Single Crystals

Abstract

Single crystals of La2CuO4 5 mm in diameter and 50 mm in length were grown at an oxygen pressure of 0.2 MPa by the traveling solvent floating zone method (TSFZ method). The as-grown crystals of La2CuO4 were superconducting, but were a mixture of a superconducting phase and an antiferromagnetic phase. The single crystals of La2CuO4 were changed reversibly from superconductors to nonsuperconductors by annealing. In the nonsuperconducting state, the single crystals of La2CuO4 were semiconducting and had a highly anisotropic resistivity, where the resistivity ratio ρ ⊥/ρ ‖ was about 28,000 at RT.