Strain-induced symmetry reduction of epitaxial La0.67Sr0.33MnO3 films
نویسندگان
چکیده
Introduction Due to spin, lattice and orbital coupling, manganese-based La1-xSrxMnO3 (LSMO) compounds exhibit unusual physical properties, such as colossal magnetoresistance and almost total spin polarization (95% at 4 K) at the composition x = 0.33 [1]. Thus, La0.67Sr0.33MnO3 has significant potential for applications in spintronic devices such as magnetic field sensors, networked environmental sensors and multiple state memory storage devices. Previous studies have shown that structural morphology, film thickness and strain induced by the lattice mismatch play a crucial role in determining the magnetic properties of LSMO thin films [2]. Substrate induced strain suppresses the Tc and Ms values of the La0.67Sr0.33MnO3 thin films from the corresponding bulk value. Yet another, less studied but important aspect that significantly influences the magnetic properties of LSMO thin films is A-site cation order. In the usual synthesis routes, random occupancy of the A site by La and Sr cations gives rise to spatial disorder. To overcome the limitations of bulk synthesis, the Materials Science Division of Argonne National Laboratory (ANL) has developed a novel method of synthesis which involves interleaving layers of LaMnO3 (LMO) and SrMnO3 (SMO) to create ordered “digitally-layered” analogues of La1-xSrxMnO3 [3]. In this manner the correlations between spin, charge and orbital degrees of freedom at the layer interface may be systematically investigated for their potential to generate states of matter that are distinctly different from those exhibited by the end members SMO and LMO or from any other part of the equilibrium SMO-LMO phase diagram. In this study, the in-plane magnetic properties of epitaxially-grown La0.67Sr0.33MnO3 thin films were investigated to elucidate the magnetostructural coupling between the film and the cubic SrTiO3 (001) substrate as a function of A-site cationic disorder.
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Magnetic signature of symmetry reduction in epitaxial La0.67Sr0.33MnO3 films
The magnetic properties of epitaxially grown La0.67Sr0.33MnO3 perovskite thin films were investigated to elucidate an unexpected broken symmetry between orthogonal [100] and [010] inplane directions, resulting from the magnetostructural coupling between the film and the cubic SrTiO3 (001) substrate. The films were synthesized by molecular beam epitaxy with either complete or zero A-site cation ...
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