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Strain engineering induced interfacial self-assembly and intrinsic exchange bias in a manganite perovskite film.

Cui B, Song C, Wang GY, Mao HJ, Zeng F, Pan F - Sci Rep (2013)

Bottom Line: The control of complex oxide heterostructures at atomic level generates a rich spectrum of exotic properties and unexpected states at the interface between two separately prepared materials.The frustration of magnetization and conductivity of manganite perovskite at surface/interface which is inimical to their device applications, could also flourish in tailored functionalities in return.The present results not only provide a strategy for producing a new class of delicately functional interface by strain engineering, but also shed promising light on fabricating the EB part of spintronic devices in a single step.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.

ABSTRACT
The control of complex oxide heterostructures at atomic level generates a rich spectrum of exotic properties and unexpected states at the interface between two separately prepared materials. The frustration of magnetization and conductivity of manganite perovskite at surface/interface which is inimical to their device applications, could also flourish in tailored functionalities in return. Here we prove that the exchange bias (EB) effect can unexpectedly emerge in a (La,Sr)MnO3 (LSMO) "single" film when large compressive stress imposed through a lattice mismatched substrate. The intrinsic EB behavior is directly demonstrated to be originating from the exchange coupling between ferromagnetic LSMO and an unprecedented LaSrMnO4-based spin glass, formed under a large interfacial strain and subsequent self-assembly. The present results not only provide a strategy for producing a new class of delicately functional interface by strain engineering, but also shed promising light on fabricating the EB part of spintronic devices in a single step.

No MeSH data available.


Related in: MedlinePlus

Direct observation of self-assembled structures in LSMO films.(a), Sketch of LAO-like, LaSrMnO4, and LSMO phases and their interfaces. (b), Typical HAADF-STEM image of the interfacial area. Interfaces between (1) LAO-like, (2) LaSrMnO4 and (3) LSMO are marked by white dashed lines. The cations are highlighted by colored circles. (c), EELS Mn L2,3 absorption edge for the region shown in the yellow frame of (b). The distance (d) in EELS is the space of the probing place and substrate surface, and the data are the average results of ±1 u.c. range. Elemental mappings by EDX measurement for the area of HAADF-STEM image (d) are shown in (e), La (red), (f), Sr (green), (g), Mn (blue), and (h), Al (cyan). The white scale bars in (d–h) represent a length of 5 nm.
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f1: Direct observation of self-assembled structures in LSMO films.(a), Sketch of LAO-like, LaSrMnO4, and LSMO phases and their interfaces. (b), Typical HAADF-STEM image of the interfacial area. Interfaces between (1) LAO-like, (2) LaSrMnO4 and (3) LSMO are marked by white dashed lines. The cations are highlighted by colored circles. (c), EELS Mn L2,3 absorption edge for the region shown in the yellow frame of (b). The distance (d) in EELS is the space of the probing place and substrate surface, and the data are the average results of ±1 u.c. range. Elemental mappings by EDX measurement for the area of HAADF-STEM image (d) are shown in (e), La (red), (f), Sr (green), (g), Mn (blue), and (h), Al (cyan). The white scale bars in (d–h) represent a length of 5 nm.

Mentions: A typical atomic resolution aberration-corrected high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image with its analysis is presented in Fig. 1. Remarkably, instead of a uniform film, the LSMO is divided into three sublattices in the order of increasing the distance from the film/substrate interface: (1) LaAlO3-like (LAO-like), (2) LaSrMnO4, and (3) LSMO. The boundaries and coherence (highlighted by colored spheres) of these three phases are clearly recognizable in the HAADF-STEM image. A magnified view of their schematic counterparts is illustrated in Fig. 1a. According to the electron energy-loss spectroscopy (EELS) (d = 0.8 and 2.0 nm) and energy dispersive x-ray spectroscopy (EDX) with a spatial accuracy of one lattice site, it is surprisingly found that the film/substrate interface is a La and Al (diffused from the substrate during the 700°C growth) enrichment region (Supplementary Fig. S1a), in contrast to the lacking of Mn and depletion of Sr ascribed to the large compressive strain [the size of Sr (Mn) is much larger than that of La (Al)], exhibiting a chemical concentration far away from LSMO. A combination of concentration characterization and lattice feature with the thickness of 6 u.c., reveals the formation of LaAlO3-like (LAO) layer just above the interface. It directly bears the strain from the substrate serving as a buffer layer.


Strain engineering induced interfacial self-assembly and intrinsic exchange bias in a manganite perovskite film.

Cui B, Song C, Wang GY, Mao HJ, Zeng F, Pan F - Sci Rep (2013)

Direct observation of self-assembled structures in LSMO films.(a), Sketch of LAO-like, LaSrMnO4, and LSMO phases and their interfaces. (b), Typical HAADF-STEM image of the interfacial area. Interfaces between (1) LAO-like, (2) LaSrMnO4 and (3) LSMO are marked by white dashed lines. The cations are highlighted by colored circles. (c), EELS Mn L2,3 absorption edge for the region shown in the yellow frame of (b). The distance (d) in EELS is the space of the probing place and substrate surface, and the data are the average results of ±1 u.c. range. Elemental mappings by EDX measurement for the area of HAADF-STEM image (d) are shown in (e), La (red), (f), Sr (green), (g), Mn (blue), and (h), Al (cyan). The white scale bars in (d–h) represent a length of 5 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3756339&req=5

f1: Direct observation of self-assembled structures in LSMO films.(a), Sketch of LAO-like, LaSrMnO4, and LSMO phases and their interfaces. (b), Typical HAADF-STEM image of the interfacial area. Interfaces between (1) LAO-like, (2) LaSrMnO4 and (3) LSMO are marked by white dashed lines. The cations are highlighted by colored circles. (c), EELS Mn L2,3 absorption edge for the region shown in the yellow frame of (b). The distance (d) in EELS is the space of the probing place and substrate surface, and the data are the average results of ±1 u.c. range. Elemental mappings by EDX measurement for the area of HAADF-STEM image (d) are shown in (e), La (red), (f), Sr (green), (g), Mn (blue), and (h), Al (cyan). The white scale bars in (d–h) represent a length of 5 nm.
Mentions: A typical atomic resolution aberration-corrected high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image with its analysis is presented in Fig. 1. Remarkably, instead of a uniform film, the LSMO is divided into three sublattices in the order of increasing the distance from the film/substrate interface: (1) LaAlO3-like (LAO-like), (2) LaSrMnO4, and (3) LSMO. The boundaries and coherence (highlighted by colored spheres) of these three phases are clearly recognizable in the HAADF-STEM image. A magnified view of their schematic counterparts is illustrated in Fig. 1a. According to the electron energy-loss spectroscopy (EELS) (d = 0.8 and 2.0 nm) and energy dispersive x-ray spectroscopy (EDX) with a spatial accuracy of one lattice site, it is surprisingly found that the film/substrate interface is a La and Al (diffused from the substrate during the 700°C growth) enrichment region (Supplementary Fig. S1a), in contrast to the lacking of Mn and depletion of Sr ascribed to the large compressive strain [the size of Sr (Mn) is much larger than that of La (Al)], exhibiting a chemical concentration far away from LSMO. A combination of concentration characterization and lattice feature with the thickness of 6 u.c., reveals the formation of LaAlO3-like (LAO) layer just above the interface. It directly bears the strain from the substrate serving as a buffer layer.

Bottom Line: The control of complex oxide heterostructures at atomic level generates a rich spectrum of exotic properties and unexpected states at the interface between two separately prepared materials.The frustration of magnetization and conductivity of manganite perovskite at surface/interface which is inimical to their device applications, could also flourish in tailored functionalities in return.The present results not only provide a strategy for producing a new class of delicately functional interface by strain engineering, but also shed promising light on fabricating the EB part of spintronic devices in a single step.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.

ABSTRACT
The control of complex oxide heterostructures at atomic level generates a rich spectrum of exotic properties and unexpected states at the interface between two separately prepared materials. The frustration of magnetization and conductivity of manganite perovskite at surface/interface which is inimical to their device applications, could also flourish in tailored functionalities in return. Here we prove that the exchange bias (EB) effect can unexpectedly emerge in a (La,Sr)MnO3 (LSMO) "single" film when large compressive stress imposed through a lattice mismatched substrate. The intrinsic EB behavior is directly demonstrated to be originating from the exchange coupling between ferromagnetic LSMO and an unprecedented LaSrMnO4-based spin glass, formed under a large interfacial strain and subsequent self-assembly. The present results not only provide a strategy for producing a new class of delicately functional interface by strain engineering, but also shed promising light on fabricating the EB part of spintronic devices in a single step.

No MeSH data available.


Related in: MedlinePlus