Effects of strain relaxation in Pr0.67Sr0.33MnO3 films probed by polarization dependent X-ray absorption near edge structure.

Bangmin Zhang,Ping Yang,Xiao Chi,T Venkatesan,Gan Moog Chow,Cheng-Jun Sun,Steve M Heald,Weinan Lin,Jingsheng Chen

doi:10.1038/srep19886

Bangmin Zhang, Ping Yang + Show 7 more

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https://doi.org/10.1038/srep19886

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Abstract

The Mn K edge X-ray absorption near edge structure (XANES) of Pr0.67Sr0.33MnO3 films with different thicknesses on (001) LaAlO3 substrate was measured, and the effects of strain relaxation on film properties were investigated. The films showed in-plane compressive and out-of-plane tensile strains. Strain relaxation occurred with increasing film thickness, affecting both lattice constant and MnO6 octahedral rotation. In polarization dependent XANES measurements using in-plane (parallel) and out-of-plane (perpendicular) geometries, the different values of absorption resonance energy Er confirmed the film anisotropy. The values of Er along these two directions shifted towards each other with increasing film thickness. Correlating with X-ray diffraction (XRD) results it is suggested that the strain relaxation decreased the local anisotropy and corresponding probability of electronic charge transfer between Mn 3d and O 2p orbitals along the in-plane and out-of-plane directions. The XANES results were used to explain the film-thickness dependent magnetic and transport properties.

Highlights

The perovskite manganites (Re1-xAxMnO3), where Re is a trivalent rare earth, and A is a divalent metal exhibit a range of interesting properties[1,2] such as high spin polarization and colossal magnetoresistance (CMR)
The main absorption structure in the Mn K edge X-ray absorption near edge structure (XANES) is due to the excitation of a Mn core 1s electron to empty 4p orbitals[18], which is sensitive to the local environment around the absorbing atom
In this work we report the Mn K edge X-ray absorption near edge structure (XANES) of Pr0.67Sr0.33MnO3 (PSMO) films of different thicknesses on (001) LaAlO3 (LAO) substrates

Summary

Introduction

The perovskite manganites (Re1-xAxMnO3), where Re is a trivalent rare earth, and A is a divalent metal exhibit a range of interesting properties[1,2] such as high spin polarization and colossal magnetoresistance (CMR). The main absorption structure in the Mn K edge XANES is due to the excitation of a Mn core 1s electron to empty 4p orbitals[18], which is sensitive to the local environment around the absorbing atom. The effects of strain relaxation on film properties may be investigated using the sensitivity of XANES to the crystal structure. In this work we report the Mn K edge X-ray absorption near edge structure (XANES) of Pr0.67Sr0.33MnO3 (PSMO) films of different thicknesses on (001) LaAlO3 (LAO) substrates. Correlating with the XRD results, it is suggested that the strain relaxation weakened the local anisotropy and the corresponding probability of charge transfer between Mn 3d and O 2p along in-plane and out-of-plane directions This is responsible for the change of Er with increasing film thickness. The transport and magnetic properties changed with strain relaxation, mediated by the change of electronic structure

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