Dimensionality Controlled Octahedral Symmetry-Mismatch and Functionalities in Epitaxial LaCoO₃/SrTiO₃ Heterostructures

Journal Article · Tue Jun 23 00:00:00 EDT 2015 · Nano Letters

DOI:https://doi.org/10.1021/acs.nanolett.5b01471· OSTI ID:1265593

Qiao, Liang ^[1]; Jang, Jae Hyuck ^[2]; Singh, David J. ^[2]; Gai, Zheng ^[3]; Xiao, Haiyan ^[4]; Mehta, Apurva ^[5]; Vasudevan, Rama K. ^[3]; Tselev, Alexander ^[3]; Feng, Zhenxing ^[6]; Zhou, Hua ^[7]; Li, Sean ^[8]; Prellier, Wilfrid ^[9]; Zu, Xiaotao ^[10]; Liu, Zijiang ^[11]; Borisevich, Albina ^[2]; Baddorf, Arthur P. ^[3]; Biegalski, Michael D. ^[3]

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1. Univ. of Manchester (United Kingdom). School of Materials; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences
4. Univ. of Electronic Science and Technology of China, Chengdu (China). School of Physical Electronics
5. SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource
6. Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Science and Engineering Division
7. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source
8. Univ. of New South Wales, Sydney, NSW (Australia). School of Materials Science and Engineering
9. Normandie Univ., Caen (France). Lab. CRISMAT
10. Univ. of Electronic Science and Technology of China, Chengdu (China). School of Physical Electronics; Univ. of Electronic Science and Technology of China, Chengdu (China). Inst. of Fundamental and Frontier Sciences
11. Lanzhou City Univ. (China). Dept. of Physics

Epitaxial strain provides a powerful approach to manipulate physical properties of materials through rigid compression or extension of their chemical bonds via lattice-mismatch. Although symmetry-mismatch can lead to new physics by stabilizing novel interfacial structures, challenges in obtaining atomic-level structural information as well as lack of a suitable approach to separate it from the parasitical lattice-mismatch have limited the development of this field. In this paper, we present unambiguous experimental evidence that the symmetry-mismatch can be strongly controlled by dimensionality and significantly impact the collective electronic and magnetic functionalities in ultrathin perovskite LaCoO₃/SrTiO₃ heterojunctions. State-of-art diffraction and microscopy reveal that symmetry breaking dramatically modifies the interfacial structure of CoO₆ octahedral building-blocks, resulting in expanded octahedron volume, reduced covalent screening, and stronger electron correlations. Such phenomena fundamentally alter the electronic and magnetic behaviors of LaCoO₃ thin-films. We conclude that for epitaxial systems, correlation strength can be tuned by changing orbital hybridization, thus affecting the Coulomb repulsion, U, instead of by changing the band structure as the common paradigm in bulks. Finally, these results clarify the origin of magnetic ordering for epitaxial LaCoO₃ and provide a route to manipulate electron correlation and magnetic functionality by orbital engineering at oxide heterojunctions.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); Electronic Science and Technology of China; NSAF Joint Foundation of China; National Natural Science Foundation of China (NNSFC); New Century Excellent Talents in University (China)
• DOE Contract Number: AC05-00OR22725; AC02-76SF00515; Y02002010401085; U1330103; 11464025; NCET-11-0906
• OSTI ID: 1265593
• Journal Information: Nano Letters, Vol. 15, Issue 7; ISSN 1530-6984
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE