Ferroelectricity with Asymmetric Hysteresis in Metallic LiOsO3 Ultrathin Films

Bulk LiOsO3 was experimentally identified as a "ferroelectric" metal where polar distortions coexist with metallicity [Shi et al., Nat. Mater. 12, 1024 (2013)]. It is generally believed that polar displacements in a ferroelectric metal cannot be switched by an external electric field. Here...

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Bibliographic Details
Published in:Physical review letters 2019-06, Vol.122 (22), p.1
Main Authors: Lu, Jinlian, Chen, Gong, Luo, Wei, Íñiguez, Jorge, Bellaiche, Laurent, Xiang, Hongjun
Format: Article
Language:English
Subjects:
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Density functional theory
Dipole moments
Electric dipoles
Electric fields
Ferroelectric domains
Ferroelectric materials
Ferroelectricity
First-principles calculations
Hysteresis loops
Metallicity
Physics
System effectiveness
Thin films
Ultrathin films
Unit cell
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Summary:Bulk LiOsO3 was experimentally identified as a "ferroelectric" metal where polar distortions coexist with metallicity [Shi et al., Nat. Mater. 12, 1024 (2013)]. It is generally believed that polar displacements in a ferroelectric metal cannot be switched by an external electric field. Here, via comprehensive density functional theory calculations, we demonstrate that a two-unit cell-thick LiOsO3 thin film exhibits a ferroelectric ground state having an out-of-plane electric dipole moment that can be switched by an external electric field. Moreover, its dipole moment-versus-electric field hysteresis loop is asymmetric because only surface Li ions' displacements are reversed by the external electric field whereas the field-induced force on inner Li atoms is nearly fully screened by itinerant electrons. As a relevant by-product of our study, we also extend the concept of "Born effective charge" to finite metallic systems, and show its usefulness to rationalize the observed effects.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.122.227601