A Low-Temperature X-Ray Diffraction Study of Structural Phase Transition in La1.86Sr0.14CuO4

Abstract

Using high-quality single crystal samples, the structural phase transition in La1.86Sr0.14CuO4 was investigated by the low-temperature X-ray diffraction method in the range from ambient temperature down to 10 K. The transition temperature from tetragonal to orthorhombic lattice was determined to be 182.5±2.5 K, and neither the monoclinic nor the new tetragonal phase was detected. Since no noticeable change was found in the peak width of (004)t during the phase transition, the shear was estimated to be confined in the direction normal to [001]t. The tilt angle between adjacent domains, determined by (220)t reflection, was of a very small value as 0.013±0.002° at 10 K. This may be related to the observed fourfold symmetry of the upper critical field (HC2) in the plane of (001)t.