期刊
NATURE
卷 533, 期 7601, 页码 68-+出版社
NATURE PORTFOLIO
DOI: 10.1038/nature17628
关键词
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资金
- National Science Foundation (NSF) under Designing Materials to Revolutionize and Engineer our Future grant [DMR-1234096]
- US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences (BES) [DE-FG02-06ER46327]
- DOE-BES [DE-SC0012375, DE-AC-02-06CH11357]
- Army Research Office [W911NF-15-1-0017]
- NSF XSEDE [ACI-1053575]
- [DMR-1056441]
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [1056441] Funding Source: National Science Foundation
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [1234096] Funding Source: National Science Foundation
Gauss's law dictates that the net electric field inside a conductor in electrostatic equilibrium is zero by effective charge screening; free carriers within a metal eliminate internal dipoles that may arise owing to asymmetric charge distributions(1). Quantum physics supports this view(2), demonstrating that delocalized electrons make a static macroscopic polarization, an ill-defined quantity in metals(3)-it is exceedingly unusual to find a polar metal that exhibits long-range ordered dipoles owing to cooperative atomic displacements aligned from dipolar interactions as in insulating phases(4). Here we describe the quantum mechanical design and experimental realization of room-temperature polar metals in thin-film ANiO(3) perovskite nickelates using a strategy based on atomic-scale control of inversion-preserving (centric) displacements(5). We predict with ab initio calculations that cooperative polar A cation displacements are geometrically stabilized with a non-equilibrium amplitude and tilt pattern of the corner-connected NiO6 octahedra-the structural signatures of perovskites-owing to geometric constraints imposed by the underlying substrate. Heteroepitaxial thin-films grown on LaAlO3 (111) substrates fulfil the design principles. We achieve both a conducting polar monoclinic oxide that is inaccessible in compositionally identical films grown on (001) substrates, and observe a hidden, previously unreported(6-10), non-equilibrium structure in thin-film geometries. We expect that the geometric stabilization approach will provide novel avenues for realizing new multifunctional materials with unusual coexisting properties.
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