Visualization of a ferromagnetic metallic edge state in manganite strips

Du, Kai; Zhang, Kai; Dong, Shuai; Wei, Wutao; Shao, Jian; Niu, Jiebin; Chen, Jinjie; Zhu, Yinyan; Lin, Huang; Yin, Xiaolu; Liou, Sy Hwang; Yin, Lifeng; Shen, Jian

doi:10.1038/ncomms7179

Cited by 53 publications

(40 citation statements)

References 26 publications

(29 reference statements)

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“…Specifically, we fabricate patterned arrays of holes, often referred to as negative dots or "antidots," (14)(15)(16) in the epitaxial LPCMO thin films. Ferromagnetic metallic (FMM) rings were observed surrounding the edges of the antidots, which is consistent with the recent discovery of FMM edge state in manganite strips (17). The magnetic measurements indicate that the magnetization of these rings is ∼16% higher than that of the film.…”

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confidence: 71%

“…The layer-by-layer growth is monitored by reflection high-energy electron diffraction. The film is postannealed ex situ in flowing oxygen at 900°C for 3 h. The antidots are fabricated by UV optical lithography and KI:HCl:H 2 O (1:1:1) wet etching (17). For consistency, six samples, including five samples with different densities of uniform circular antidot (radius 1.2 μm) arrays and one control sample with no antidot, are fabricated from one single 5-mm × 5-mm film.…”

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confidence: 99%

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Manipulating electronic phase separation in strongly correlated oxides with an ordered array of antidots

Zhang

Líu

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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The interesting transport and magnetic properties in manganites depend sensitively on the nucleation and growth of electronic phase-separated domains. By fabricating antidot arrays in La 0.325 Pr 0.3 Ca 0.375 MnO 3 (LPCMO) epitaxial thin films, we create ordered arrays of micrometer-sized ferromagnetic metallic (FMM) rings in the LPCMO films that lead to dramatically increased metal-insulator transition temperatures and reduced resistances. The FMM rings emerge from the edges of the antidots where the lattice symmetry is broken. Based on our Monte Carlo simulation, these FMM rings assist the nucleation and growth of FMM phase domains increasing the metal-insulator transition with decreasing temperature or increasing magnetic field. This study points to a way in which electronic phase separation in manganites can be artificially controlled without changing chemical composition or applying external field.manganites | metal-insulator transition | electronic phase separation | antidot | magnetization E lectronic phase separation (EPS) is a striking phenomenon that commonly occurs in strongly correlated materials such as highTc oxides and colossal magnetoresistive (CMR) manganites (1, 2). Because EPS originates from strong coupling between spin, charge, orbital, and lattice, studies of EPS may reveal the fundamentals of strong electronic interactions in complex oxides (3, 4). Moreover, physical properties of complex oxides often depend sensitively on the details of EPS domains, including their size, density, and growth kinetics upon changing physical parameters. Therefore, a great effort has been devoted to study the EPS phenomena and engineer the domains in complex oxides (5, 6).With the help of real-space imaging methods, the size of EPS domains of oxide films has been shown to range from ∼10 nm to a few hundred nanometers, depending on the material (7,8). The spatial distribution of the EPS domains is often random, and their shape can be tuned by external strain (9, 10) or the symmetry of substrates (11). Recently, it has been shown that the nucleation and growth of EPS domains in manganites are controllable by applying local external fields (magnetic or electric) (12, 13). What has not been explored is the effect of ordered arrays of artificially structured domains on EPS.In this work, we show that ordered arrays of EPS domains can be created with controllable size, shape, and density in La 0.325 Pr 0.3-Ca 0.375 MnO 3 (LPCMO), a prototypical CMR material. Specifically, we fabricate patterned arrays of holes, often referred to as negative dots or "antidots," (14-16) in the epitaxial LPCMO thin films. Ferromagnetic metallic (FMM) rings were observed surrounding the edges of the antidots, which is consistent with the recent discovery of FMM edge state in manganite strips (17). The magnetic measurements indicate that the magnetization of these rings is ∼16% higher than that of the film. With the increase of antidot density, the LPCMO thin films exhibit considerably higher metalinsulator transition (MIT) temperature a...

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confidence: 99%

Manipulating electronic phase separation in strongly correlated oxides with an ordered array of antidots

Zhang

Líu

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…Notable examples include abrupt resistance switching [2,3], reentrant metal-insulator transitions [4], enhanced ferromagnetic edge states [5], and tunable domain structures [6] in manganite wires and islands.…”

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Giant Enhancement of Magnetic Anisotropy in Ultrathin Manganite Films via Nanoscale 1D Periodic Depth Modulation

et al. 2016

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“…1. Considering the fact that we have never observed pure COI phase in the 500-nm disks, we believe this phenomenon may be caused by the existence of the ferromagnetic metallic edge state in the LPCMO system (22), which assists the 500-nm disk to be in pure ferromagnetic state when a single state is energetically preferred in the 500-nm disk.…”

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confidence: 99%

“…The LPCMO system is chosen because of its well-known large length scale of EPS domains (approximately a micrometer) (21), which allows us to conveniently fabricate LPCMO epitaxial thin films into disks with diameters that are smaller than the EPS domain size. In LPCMO bulk (21) and thin films (6,22), the EPS state was observed to be the low-temperature ground state. Using magnetic force microscope, we observe that the EPS state remains to be the ground state in disks with the size of 800 nm in diameter or larger but vanishes in the 500-nm-diameter disks whose size is distinctly smaller than the characteristic length scale of the EPS domains.…”

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Emerging single-phase state in small manganite nanodisks

Shao

Líu

Zhang

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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In complex oxides systems such as manganites, electronic phase separation (EPS), a consequence of strong electronic correlations, dictates the exotic electrical and magnetic properties of these materials. A fundamental yet unresolved issue is how EPS responds to spatial confinement; will EPS just scale with size of an object, or will the one of the phases be pinned? Understanding this behavior is critical for future oxides electronics and spintronics because scaling down of the system is unavoidable for these applications. In this work, we use La 0.325 Pr 0.3 Ca 0.375 MnO 3 (LPCMO) single crystalline disks to study the effect of spatial confinement on EPS. The EPS state featuring coexistence of ferromagnetic metallic and charge order insulating phases appears to be the low-temperature ground state in bulk, thin films, and large disks, a previously unidentified ground state (i.e., a single ferromagnetic phase state emerges in smaller disks). The critical size is between 500 nm and 800 nm, which is similar to the characteristic length scale of EPS in the LPCMO system. The ability to create a pure ferromagnetic phase in manganite nanodisks is highly desirable for spintronic applications.manganites | electronic phase separation | magnetization | single phase O wing to strong coupling between spin, charge, orbital, and lattice (1, 2), different electronic phases often coexist spatially in strongly correlated materials known as electronic phase separation (EPS) (3, 4). For colossal magnetoresistance (CMR) manganites, EPS has been observed to have strong influence on the global magnetic and transport properties (5, 6). Regarding the physical origin of EPS, it has been shown theoretically that quenched disorder can lead to inhomogeneous states in manganites (1, 3, 7). Once long-range effects such as coulombic forces (8), cooperative oxygen octahedral distortions (9), or strain effects (10) are included, calculations show infinitesimal disorder (8, 11) or even no explicit disorder (10) may lead to EPS. Within a phenomenological Ginzburg-Landau theory, it has been shown that EPS is intrinsic in complex systems as a thermodynamic equilibrium state (12).Although the details of the origin of the EPS remain as a matter of dispute, its very existence as a new form of electronic state has been well accepted. The length scale of the EPS has been observed to vary widely from nanometers to micrometers depending on many parameters that can affect the competition between different electronic phases (13)(14)(15)(16)(17)(18)(19)(20). It is thus of great interest to examine whether the EPS state still exists as the system is scaled down, especially when the spatial dimension of the system is smaller than the length scale of the EPS domains.In this work, we use La 0.325 Pr 0.3 Ca 0.375 MnO 3 (LPCMO) as a prototype system to show a spatial confinement-induced transition from the EPS state to a single ferromagnetic phase state. The LPCMO system is chosen because of its well-known large length scale of EPS domains (approximately a micromet...

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Visualization of a ferromagnetic metallic edge state in manganite strips

Cited by 53 publications

References 26 publications

Manipulating electronic phase separation in strongly correlated oxides with an ordered array of antidots

Manipulating electronic phase separation in strongly correlated oxides with an ordered array of antidots

Giant Enhancement of Magnetic Anisotropy in Ultrathin Manganite Films via Nanoscale 1D Periodic Depth Modulation

Emerging single-phase state in small manganite nanodisks

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