Step Terrace Tuned Anisotropic Transport Properties of Highly Epitaxial LaBaCo₂O_5.5+δ Thin Films on Vicinal SrTiO₃ Substrates

Abstract

Highly epitaxial LaBaCo2O5.5+δ (LBCO) thin films were grown on different miscut (001) SrTiO3 substrates (miscut angle of 0.5°, 3.0°, and 5.0°) to study the substrate surface step terrace effect on the in-plane electrical transport properties. The microstructure studies by X-ray diffraction and transmission electron microscopy indicate that the as-grown films are A-site disordered cubic perovskite structures with the c-axis highly oriented along the film growth direction. The four-probe scanning tunneling microscopy (STM) studies show that the LBCO thin films grown on the vicinal SrTiO3 substrates have a typical semiconductor behavior with the substrate surface terrace step inducing anisotropic electronic transport properties. These results indicate that in highly epitaxial thin films the surface terrace step induced local strains can play an important role in controlling the electronic transport properties and the anisotropic nature.

Surface step terrace tuned microstructures and dielectric properties of highly epitaxial CaCu3Ti4O12 thin films on vicinal LaAlO3 substrates

“…To understand the mechanism of the lattice deformation of CCTO thin films grown on vicinal substrates, mismatching strains introduced by surface step terraces should be taken into consideration21222324. As demonstrated by the SPM images in Fig.…”

“…In the last decade, techniques with controllable strains in epitaxial thin films have been widely investigated121314151617181920. Recently, the surface-step-terrace (SST) model was developed to tune the interface strain by controlling the unit cell matching between the film and the surface step terrace dimension of the substrate21222324. In this model, there are two kinds of mismatch between the film and the vicinal substrate: the lattice misfit between the film and the substrate and the unit cell mismatch between the epitaxial film and the surface step terrace dimension of the substrate.…”

Manipulation of Optical Transmittance by Ordered-Oxygen-Vacancy in Epitaxial LaBaCo2O5.5+δ Thin Films

“…In order to further investigate the physical properties in such complex cobaltite system, we have fabricated the high quality epitaxial thin films on various substrates and studied its microstructure and physical properties. The epitaxial LBCO thin films exhibit several impressing improvement of physical properties, for example, a much larger magnetoresistance value was observed on epitaxial thin films than those from its bulk material at low temperatures; besides, LBCO thin films possess extraordinary sensitivity to reducing/oxidizing environments, especially an exceedingly fast redox reaction at high temperature171819202122232425262728. Therefore, LBCO thin films are promising candidates for the development of the gas sensors in reducing/oxidizing environments.…”

Gas Sensing Properties of Epitaxial LaBaCo2O5.5+δ Thin Films

“…To under these physics nature, single crystalline LBCO thin films are required. Recently, highly epitaxial single crystalline LBCO thin films were fabricated on various substrates, such as (001) LaAlO 3 (LAO)16, (001) SrTiO 3 171819, (001) MgO2021, and (110) NdGaO 3 22. The LBCO films not only exhibit a much larger magnetoresistance value than those from various phases of its bulk material, but also possess an extraordinary sensitivity to H 2 and O 2 , especially an exceedingly fast redox reaction at high temperature and a superfast oxygen vacancy exchange diffusion chemical dynamics1623.…”