Twinned LaAlO 3 substrate effect on epitaxially grown La–Ca–Mn–O thin film crystalline structure

Abstract

La–Ca–Mn–O (LCMO) thin film was epitaxially grown on LaAlO 3 (1 0 0) substrate using RF magnetron sputtering. The epitaxial relationship between LCMO and LaAlO 3 (LAO), was characterized using MeV 4 He 2+ backscattering (BS)/channeling and a 4-circle X-ray diffractometer (XRD). The LCMO film deposited at 600°C with an RF power of 100 W showed the channeling minimum yield of 4.98% indicating its excellent crystallinity and high c-axis orientation. Through channeling angular scan measurement, it is confirmed that the 145 nm thick LCMO thin film conserved the compressive stress. The FWHM value of LCMO (2 0 0) peak in XRD θ-rocking is mainly influenced by the twin structure of LAO substrate. It is also interesting that the twin angle of LAO substrate, 0.18°, is very close to the separation of two peaks, 0.20°, in XRD θ-rocking scan on LCMO (2 0 0) peak. From these results, it is suggested that these two subpeaks in XRD θ–2 θ curve were originated from each twinned plane rather than coexistence of strained and relaxed layers. In addition, the FWHM of LCMO (2 0 0) peak obtained from high-resolution XRD θ-rocking, 0.147°, is smaller than any value ever reported.