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Title: Surface Effects on the Orbital Order in the Single-Layered Manganite La0.5Sr1.5MnO4

Abstract

The question of how bulk electronic order is terminated at a surface is an intriguing one, and one with possible practical implications--for example in nanoscaled systems that may be characterized by their surface behaviour. One example of such order is orbital order, and in principle it should be possible to probe the termination of this order with surface X-ray scattering. Here, we report the first observation of the scattering arising from the termination of bulk orbital order at the surface of a crystal--so-called 'orbital truncation rods'. The measurements, carried out on a cleaved perovskite, La0.5Sr1.5MnO4, reveal that whereas the crystallographic surface is atomically smooth, the orbital 'surface', which is observed through the atomic displacements caused by the orbital order, is much rougher, with a typical scale of the surface roughness of approx7 Angstroms . Interestingly, the temperature dependence of this scattering shows evidence of a surface-induced second-order transition.

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
960060
Report Number(s):
BNL-83046-2009-JA
TRN: US201016%%1204
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature Materials; Journal Volume: 6; Journal Issue: 12
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ATOMIC DISPLACEMENTS; LANTHANUM OXIDES; MANGANESE OXIDES; MANGANATES; PEROVSKITE; ROUGHNESS; SCATTERING; STRONTIUM OXIDES; TEMPERATURE DEPENDENCE; SURFACES; national synchrotron light source

Citation Formats

Wakabayashi,Y., Upton, M., Grenier, S., Hill, J., Nelson, C., Kim, J., Ryan, P., Goldman, A., Zheng, H., and Mitchell, J.. Surface Effects on the Orbital Order in the Single-Layered Manganite La0.5Sr1.5MnO4. United States: N. p., 2007. Web. doi:10.1038/nmat2061.
Wakabayashi,Y., Upton, M., Grenier, S., Hill, J., Nelson, C., Kim, J., Ryan, P., Goldman, A., Zheng, H., & Mitchell, J.. Surface Effects on the Orbital Order in the Single-Layered Manganite La0.5Sr1.5MnO4. United States. doi:10.1038/nmat2061.
Wakabayashi,Y., Upton, M., Grenier, S., Hill, J., Nelson, C., Kim, J., Ryan, P., Goldman, A., Zheng, H., and Mitchell, J.. Mon . "Surface Effects on the Orbital Order in the Single-Layered Manganite La0.5Sr1.5MnO4". United States. doi:10.1038/nmat2061.
@article{osti_960060,
title = {Surface Effects on the Orbital Order in the Single-Layered Manganite La0.5Sr1.5MnO4},
author = {Wakabayashi,Y. and Upton, M. and Grenier, S. and Hill, J. and Nelson, C. and Kim, J. and Ryan, P. and Goldman, A. and Zheng, H. and Mitchell, J.},
abstractNote = {The question of how bulk electronic order is terminated at a surface is an intriguing one, and one with possible practical implications--for example in nanoscaled systems that may be characterized by their surface behaviour. One example of such order is orbital order, and in principle it should be possible to probe the termination of this order with surface X-ray scattering. Here, we report the first observation of the scattering arising from the termination of bulk orbital order at the surface of a crystal--so-called 'orbital truncation rods'. The measurements, carried out on a cleaved perovskite, La0.5Sr1.5MnO4, reveal that whereas the crystallographic surface is atomically smooth, the orbital 'surface', which is observed through the atomic displacements caused by the orbital order, is much rougher, with a typical scale of the surface roughness of approx7 Angstroms . Interestingly, the temperature dependence of this scattering shows evidence of a surface-induced second-order transition.},
doi = {10.1038/nmat2061},
journal = {Nature Materials},
number = 12,
volume = 6,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • The question of how bulk electronic order is terminated at a surface is an intriguing one, and one with possible practical implications--for example in nanoscaled systems that may be characterized by their surface behavior. One example of such order is orbital order, and in principle it should be possible to probe the termination of this order with surface X-ray scattering. Here, we report the first observation of the scattering arising from the termination of bulk orbital order at the surface of a crystal--so-called 'orbital truncation rods'. The measurements, carried out on a cleaved perovskite, La{sub 0.5}Sr{sub 1.5}MnO{sub 4}, reveal thatmore » whereas the crystallographic surface is atomically smooth, the orbital 'surface', which is observed through the atomic displacements caused by the orbital order, is much rougher, with a typical scale of the surface roughness of 7 {angstrom}. Interestingly, the temperature dependence of this scattering shows evidence of a surface-induced second-order transition.« less
  • The top layer of a cleaved surface of the single layered manganite La{sub 0.5}Sr{sub 1.5}MnO{sub 4} is measured with crystal truncation rod scattering. Knowledge of the surface structure of strongly correlated electron systems is needed for nano-science and device application of such systems. The result shows that the cleaved surface is terminated by La/Sr layer and has little surface roughness.
  • Epitaxial La{sub 1-x}Sr{sub x}MnO{sub 3} {center_dot} SrO (x = 1/3) films were synthesized as random alloys and cation-ordered analogs to probe how cation ordering affects the properties of a two dimensional manganite. The films show evidence for a spin glass like phase below 20 K and weak ferromagnetic ordering up to 130 K. There is a dramatic difference in magnetic anisotropy and the low temperature transport mechanism depending on the cation order, which is consistent with differences in Mn 3d orbital occupancies. This work indicates that cation ordering can significantly alter the Mn 3d orbital ground state in these correlatedmore » electron systems.« less
  • The striking anisotropy observed in Huang scattering distributions near the intense Bragg reflections of La{sub 1.2}Sr{sub 1.8}Mn{sub 2}O{sub 7} is shown to be the result of orbitally polarized polarons in the paramagnetic insulating state above T{sub c}. X-ray single-crystal diffuse scattering patterns from this bilayered colossal magnetoresistive manganite are calculated in terms of the polaronic local structure and compared with experimental measurements. At 300 K, the polaronic e{sub g} electrons occupy 'out-of-plane' (i.e., 3z{sup 2}-r{sup 2}) orbitals, leading to MnO{sub 6} octahedra that are Jahn-Teller elongated along the c axis, perpendicular to the perovskite layers. Between 300 K and T{submore » c}, however, the 'orbital polarization' is shown to shift into the a-b plane (i.e., 3x{sup 2}-r{sup 2} and 3y{sup 2}-r{sup 2} orbitals), allowing the formation of nanoscale polaron correlations above T{sub c}.« less