Review on ferroelectric/polar metals

Abstract

The possibility of reconciliation between seemingly mutually exclusive properties in one system can not only lead to theoretical breakthroughs but also potential novel applications. The research on the coexistence of two purportedly contra-indicated properties, ferroelectricity/polarity and conductivity, proposed by Anderson and Blount over 50 years ago was recently revitalized by the discovery of the first unambiguous polar metal LiOsO 3 and further fueled by the demonstration of the first switchable ferroelectric metal WTe 2 . In this review, we first discuss the reasons why the coexistence of ferroelectricity/polarity and conductivity have been deemed incompatible, followed by a review on the history of ferroelectric/polar metals. Secondly, we review the important milestones along with the corresponding mechanisms for the ferroelectric/polar metallic phases in these materials.Thirdly, we summarize the design approaches for ferroelectric/polar metals. Finally, we discuss the future prospects and potential applications of ferroelectric/polar metals.

Tunable Microwave Conductance of Nanodomains in Ferroelectric PbZr0.2Ti0.8O3 Thin Film

“…Polarization switching has been employed in capacitive ferroelectric memories, where opposed. [23,24] In turn, it is highly nontrivial to establish good electrical contact to the domain wall. [25] In fact, charged domain walls may reconstruct in the contact region preventing good metallic contact from being established on an intrinsic level.…”

Ferroelectricity promoted by cation/anion divacancies in SrMnO3

“…Strain-dependent ferroelectricity in stoichiometric G-AFM SMO thin films was previously reported by Marthinsen et al 12 Here, we evaluate polar instabilities also for the FM phase but note that its metallicity will preclude ferroelectric switching, an unstable polar mode indicating merely a polar metal state. 47,48 Fig. 2 shows the evolution of SMO polar-mode frequencies as a function of strain.…”

Prediction of Strong Converse Magnetoelectric Effect in Nb‐Doped BaTiO3‐Based Polar Metals

“…Recently, another pair of contraindicated propertiesFE and metallicityhas strongly attracted attention from the research community, which is called polar metal (or ferroelectric metal). [ 18 ] Moreover, theoretical predictions and experimental observations have confirmed that the polarization reversal can be achieved in polar metals LiOsO 3 ultrathin film, [ 19 ] Bi 5 Ti 5 O 17 , [ 20 ] and 2D WTe 2 [ 21 ] by applying an electric field. In 2015, Puggioni et al [ 22 ] predicted that (LiOsO 3 ) 1 /(LiNbO 3 ) 1 superlattice polar metal exhibits strong ME coupling as well as high ferroelectric Curie temperature (927 K) and Néel temperature (379 K).…”