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Title: Nature and evolution of incommensurate charge order in manganites visualized with cryogenic scanning transmission electron microscopy

Abstract

Incommensurate charge order in hole-doped oxides is intertwined with exotic phenomena such as colossal magnetoresistance, high-temperature superconductivity, and electronic nematicity. Here, we map, at atomic resolution, the nature of incommensurate charge–lattice order in a manganite using scanning transmission electron microscopy at room temperature and cryogenic temperature (~93 K). In diffraction, the ordering wave vector changes upon cooling, a behavior typically associated with incommensurate order. However, using real space measurements, we discover that the ordered state forms lattice-locked regions over a few wavelengths interspersed with phase defects and changing periodicity. The cations undergo picometer-scale (~6 pm to 11 pm) transverse displacements, suggesting that charge–lattice coupling is strong. We further unearth phase inhomogeneity in the periodic lattice displacements at room temperature, and emergent phase coherence at 93 K. Such local phase variations govern the long-range correlations of the charge-ordered state and locally change the periodicity of the modulations, resulting in wave vector shifts in reciprocal space. These atomically resolved observations underscore the importance of lattice coupling and phase inhomogeneity, and provide a microscopic explanation for putative “incommensurate” order in hole-doped oxides.

Authors:
ORCiD logo [1];  [1];  [2];  [2];  [2];  [3];  [1]
  1. Cornell Univ., Ithaca, NY (United States)
  2. Rutgers Univ., Piscataway, NJ (United States)
  3. Cornell Univ., Ithaca, NY (United States); Univ. of Michigan, Ann Arbor, MI (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC); US Air Force Office of Scientific Research (AFOSR); National Science Foundation (NSF)
OSTI Identifier:
1559788
Grant/Contract Number:  
AC02-05CH11231; DGE-1144153; NSFMRI-1429155
Resource Type:
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 115; Journal Issue: 7; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; charge order; incommensurate; manganite; electron microscopy; cryogenic STEM

Citation Formats

El Baggari, Ismail, Savitzky, Benjamin H., Admasu, Alemayehu S., Kim, Jaewook, Cheong, Sang -Wook, Hovden, Robert, and Kourkoutis, Lena F. Nature and evolution of incommensurate charge order in manganites visualized with cryogenic scanning transmission electron microscopy. United States: N. p., 2018. Web. doi:10.1073/pnas.1714901115.
El Baggari, Ismail, Savitzky, Benjamin H., Admasu, Alemayehu S., Kim, Jaewook, Cheong, Sang -Wook, Hovden, Robert, & Kourkoutis, Lena F. Nature and evolution of incommensurate charge order in manganites visualized with cryogenic scanning transmission electron microscopy. United States. doi:10.1073/pnas.1714901115.
El Baggari, Ismail, Savitzky, Benjamin H., Admasu, Alemayehu S., Kim, Jaewook, Cheong, Sang -Wook, Hovden, Robert, and Kourkoutis, Lena F. Tue . "Nature and evolution of incommensurate charge order in manganites visualized with cryogenic scanning transmission electron microscopy". United States. doi:10.1073/pnas.1714901115. https://www.osti.gov/servlets/purl/1559788.
@article{osti_1559788,
title = {Nature and evolution of incommensurate charge order in manganites visualized with cryogenic scanning transmission electron microscopy},
author = {El Baggari, Ismail and Savitzky, Benjamin H. and Admasu, Alemayehu S. and Kim, Jaewook and Cheong, Sang -Wook and Hovden, Robert and Kourkoutis, Lena F.},
abstractNote = {Incommensurate charge order in hole-doped oxides is intertwined with exotic phenomena such as colossal magnetoresistance, high-temperature superconductivity, and electronic nematicity. Here, we map, at atomic resolution, the nature of incommensurate charge–lattice order in a manganite using scanning transmission electron microscopy at room temperature and cryogenic temperature (~93 K). In diffraction, the ordering wave vector changes upon cooling, a behavior typically associated with incommensurate order. However, using real space measurements, we discover that the ordered state forms lattice-locked regions over a few wavelengths interspersed with phase defects and changing periodicity. The cations undergo picometer-scale (~6 pm to 11 pm) transverse displacements, suggesting that charge–lattice coupling is strong. We further unearth phase inhomogeneity in the periodic lattice displacements at room temperature, and emergent phase coherence at 93 K. Such local phase variations govern the long-range correlations of the charge-ordered state and locally change the periodicity of the modulations, resulting in wave vector shifts in reciprocal space. These atomically resolved observations underscore the importance of lattice coupling and phase inhomogeneity, and provide a microscopic explanation for putative “incommensurate” order in hole-doped oxides.},
doi = {10.1073/pnas.1714901115},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 7,
volume = 115,
place = {United States},
year = {2018},
month = {1}
}

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