Polar metals as electrodes to suppress the critical-thickness limit in ferroelectric nanocapacitors

Puggioni, Danilo; Giovannetti, Gianluca; Rondinelli, James M.

doi:10.1063/1.5049607

Cited by 30 publications

(28 citation statements)

References 47 publications

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“…The first observation of polarization switching in a ferroelectric (semi-)metal is even more recent [11,12]. The interest in polar and ferroelectric-like metals is continuing to increase in both bulk and heterostructures [13][14][15][16][17][18][19][20][21][22][23][24] and they continue to promise both a fertile playground for interesting emergent phenomena (including, but not limited to mixed singlet-triplet superconductivity [25] and novel optical effects [26]), and immediate relevance to applications as polar electrodes [27].…”

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confidence: 99%

Free-Carrier-Induced Ferroelectricity in Layered Perovskites

Birol

2021

Phys. Rev. Lett.

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Doping ferroelectrics with carriers is often detrimental to polarization. This makes the design and discovery of metals that undergo a ferroelectric-like transition challenging. In this letter, we show from first principles that the oxygen octahedral rotations in perovskites are often enhanced by electron doping, and this can be used as a means to strengthen the structural polarization in certain hybrid-improper ferroelectrics -compounds in which the polarization is not stabilized by the long range Coulomb interactions but is instead induced by a trilinear coupling to octahedral rotations. We use this design strategy to predict a cation ordered Ruddlesden-Popper compound that can be driven into a metallic ferroelectric-like phase via electrolyte gating.

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confidence: 99%

Free-Carrier-Induced Ferroelectricity in Layered Perovskites

Birol

2021

Phys. Rev. Lett.

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“…It has, however, been proposed that a robust polarization in ultrathin films—thinner than 30 unit cells (u.c. )—can be promoted by interface defects ( 13 , 14 ), distortions in the metallic buffer ( 15 , 16 ), or the interfacial chemical bonding ( 17 – 19 ). Interface effects can also influence the character of the polarization across the whole film in the ultrathin regime.…”

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confidence: 99%

Interface and surface stabilization of the polarization in ferroelectric thin films

Gattinoni

Strkalj

Härdi

et al. 2020

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

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Ferroelectric perovskites present a switchable spontaneous polarization and are promising energy-efficient device components for digital information storage. Full control of the ferroelectric polarization in ultrathin films of ferroelectric perovskites needs to be achieved in order to apply this class of materials in modern devices. However, ferroelectricity itself is not well understood in this nanoscale form, where interface and surface effects become particularly relevant and where loss of net polarization is often observed. In this work, we show that the precise control of the structure of the top surface and bottom interface of the thin film is crucial toward this aim. We explore the properties of thin films of the prototypical ferroelectric lead titanate (PbTiO3) on a metallic strontium ruthenate (SrRuO3) buffer using a combination of computational (density functional theory) and experimental (optical second harmonic generation) methods. We find that the polarization direction and strength are influenced by chemical and electronic processes occurring at the epitaxial interface and at the surface. The polarization is particularly sensitive to adsorbates and to surface and interface defects. These results point to the possibility of controlling the polarization direction and magnitude by engineering specific interface and surface chemistries.

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“…Therefore, we study a BPTO/PbTiO 3 heterostructure, in which both BPTO polar displacements and PbTiO 3 polarization are parallel to the interface. We will show that different from previously studied ferroelectric/polar-metal heterostructures 2,4,43,44 , multiple states with different relative orientations of BiPbTi 2 O 6 polar displacements and PbTiO 3 polarization can be stabilized. When an electric field is applied to switch the polarization of PbTiO 3 , a finite energy barrier exists for BPTO to change its polar displacements by 180°.…”

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confidence: 61%

Design of a multifunctional polar metal via first-principles high-throughput structure screening

Fang

Chen

2020

Commun Mater

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Intrinsic polar metals are rare, especially in oxides, because free electrons screen electric fields in a metal and eliminate the internal dipoles that are needed to break inversion symmetry. Here we use first-principles high-throughput structure screening to predict a new polar metal in bulk and thin film forms. After screening more than 1000 different crystal structures, we find that ordered BiPbTi 2 O 6 can crystallize in three polar and metallic structures, which can be transformed between via pressure or strain. In a heterostructure of layered BiPbTi 2 O 6 and PbTiO 3 , multiple states with different relative orientations of BiPbTi 2 O 6 polar displacements, and PbTiO 3 polarization, can be stabilized. At room temperature, the interfacial coupling enables electric fields to first switch PbTiO 3 polarization and subsequently drive 180°change of BiPbTi 2 O 6 polar displacements. At low temperatures, the heterostructure provides a tunable tunnelling barrier and might be used in multi-state memory devices.

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Polar metals as electrodes to suppress the critical-thickness limit in ferroelectric nanocapacitors

Cited by 30 publications

References 47 publications

Free-Carrier-Induced Ferroelectricity in Layered Perovskites

Free-Carrier-Induced Ferroelectricity in Layered Perovskites

Interface and surface stabilization of the polarization in ferroelectric thin films

Design of a multifunctional polar metal via first-principles high-throughput structure screening

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