Structure, Phonon Vibration, and Spin Correlation of LaBa2Cu3-xCoxOy

Abstract

Polycrystalline samples LaBa2Cu3−xCoxOy (0 ≤ x ≤ 1.0) were synthesized by solid state reaction method. The structure, phonon vibration, conduction, and spin correlation were investigated by means of X-ray diffraction, infrared spectra, resistivity, and electron spin resonance. It is found that there are orthorhombic–tetragonal and tetragonal–orthorhombic structural transitions with Co doping, and the conduction behavior changes from metallic to semiconducting. With the increase of Co content, the Cu(1)—O(1) phonon mode around 531 cm−1 softens, the Cu(2)—O(2) phonon mode around 657 cm−1 hardens, and the Cu(1)—O(4) mode around 583 cm−1 is nearly unchanged. The Cu2+ spins tend to localize with Co doping. The changes in structure, phonon vibration, and spin correlation with Co doping are analyzed and discussed.