Magnetic properties of La\u3csub\u3e0.60\u3c/sub\u3eSr\u3csub\u3e0.40\u3c/sub\u3eMnO\u3csub\u3e3\u3c/sub\u3e thin films on SrTiO\u3csub\u3e3\u3c/sub\u3e and buffered Si substrates with varying thickness

摘要

La0.60Sr0.40MnO3 (LSMO) thin films of varying thickness from 12 to 55 nm were deposited using the pulsed-laser deposition technique onto single-crystalline SrTiO3 (STO) and STO-buffered Si substrates. The T c of LSMO films grown on STO-buffered Si substrates decreases faster than films directly grown on STO with decreasing film thickness. The LSMO/STO film with thickness of 55 nm shows T c at about 360 K, which is close to the bulk value, whereas T c LSMO film on STO-buffered Si film of similar thickness is reduced to 320 K. This difference is attributed to the strain and interfacial disorders in LSMO film on STO/Si. The film surface morphology is influenced by the film thickness. Oxygenation of LSMO films on STO-buffered Si affects the T c minimally but improved the overall magnetization of the films due to better oxygenation, which is also the case for postannealing the sample at elevated temperatures. The thermomagnetic history effects observed in LSMO films of STO-buffered Si indicate the presence of inhomogeneity, mostly at the interface, which influences the magnetic properties significantly.