Improper ferroelectricity in perovskite oxide artificial superlattices

Bousquet, Éric; Dawber, Matthew; Stucki, Nicolas; Lichtensteiger, Céline; Hermet, Patrick; Gariglio, Stefano; Triscone, Jean‐Marc; Ghosez, Philippe

doi:10.1038/nature06817

Cited by 845 publications

(807 citation statements)

References 34 publications

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“…41 As a result of these approximations, we were able to construct our superlattice potentials by using the models for bulk PTO and STO to describe the interactions within the layers, The parameters of our models for bulk PTO and STO were computed from first principles as described in ref. 24.…”

Section: Atomistic Simulations Of Pbtio 3 /Srtio 3 Superlatticesmentioning

confidence: 99%

Negative capacitance in multidomain ferroelectric superlattices

Zubko¹,

Wojdeł²,

Hadjimichael³

et al. 2016

Nature

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318

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*These authors contributed equally to this work.The stability of the spontaneous electrical polarisation characteristic of ferroelectrics is fundamental to a multitude of their current applications, ranging from the simple electrical cigarette lighter to non-volatile random access memories 1 . Yet, the technological potential of these materials is far from being exhausted as research on nanoscale ferroelectrics reveals their properties to be profoundly different from those in bulk, giving rise to fascinating new phenomena with exciting prospects for future 2 devices 2-4 . As ferroelectrics become thinner, maintaining a stable polarisation becomes increasingly challenging. On the other hand, intentionally destabilising this polarisation can cause the effective electrical permittivity of a ferroelectric to become negative 5 , enabling it to behave as a negative capacitance when integrated in a heterostructure.Negative capacitance has been garnering increasing attention following the realisation that it could be exploited to overcome fundamental limitations on the power consumption of field effect transistors 6 . Experimentally, however, demonstrations of this phenomenon are still contentious 7 . The prevalent interpretations based on homogeneous polarisation models are difficult to reconcile with the expected strong tendency for domain formation 8,9 , while the effect of domains on negative capacitance has received surprisingly little attention 5,10-12 . Here we report the observation of negative capacitance in a model system of multidomain ferroelectric-dielectric superlattices across a wide range of temperatures, in both the ferroelectric and paraelectric phases. Using a phenomenological model we show that domain-wall motion not only gives rise to negative permittivity but can also enhance, rather than limit, its temperature range. Furthermore, our first-principles-based atomistic simulations provide detailed microscopic insight on the origin of this phenomenon, identifying the dominant contribution of near-interface layers and paving the way for its future exploitation.Negative capacitance (NC) has its origins in the imperfect screening of the spontaneous polarisation 5,10,13,14 . Imperfect screening is intrinsic to any semiconductor-ferroelectric or even metal-ferroelectric interfaces because of their finite effective screening lengths 15,16 .Alternatively, it can be engineered in a controlled manner by deliberately inserting a dielectric layer of relative permittivity ߳ ௗ between the ferroelectric and the electrodes as suggested by Salahuddin and Data 6 and shown in Fig. 1a. The physical separation of the 3 ferroelectric bound charge from the metallic screening charges creates a depolarizing field inside the ferroelectric, destabilizing the polarisation and lowering the ferroelectric transition temperature. The effect of the dielectric layer can be understood by considering the free energy of the bilayer capacitor with the usual assumption of a uniform polarisation ܲ (see Methods). Below the bulk transitio...

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Section: Atomistic Simulations Of Pbtio 3 /Srtio 3 Superlatticesmentioning

confidence: 99%

Negative capacitance in multidomain ferroelectric superlattices

Zubko¹,

Wojdeł²,

Hadjimichael³

et al. 2016

Nature

Self Cite

318

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“…The coupling between antiferrodistortive (AFD) rotations and the local dipole moments are rarely investigated, yet such interactions have been shown to influence Curie temperatures and phases that can produce improper ferroelectrics [12,44]. It has recently been proposed that control of AFD chiralities could be used in novel technologies such as four-state memory making the identity of methods to control AFD behaviour at atomic scales paramount [45].…”

Section: Novel Properties Of Bc D and Abc D Domainsmentioning

confidence: 99%

Novel high-temperature ferroelectric domain morphology in PbTiO₃ ultrathin films

Chapman

Kimmel

Duffy

2017

Phys. Chem. Chem. Phys.

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Exotic domain morphologies in ferroic materials are an exciting avenue for the development of novel nanoelectronics. In this work we have used large scale molecular dynamics to construct a strain-temperature phase diagram of the domain morphology of PbTiO3 ultrathin films. Sampling a wide interval of strain values over a temperature range up to the Curie temperature Tc, we found that epitaxial strain induces the formation of a variety of closure-and in-plane domain morphologies. The local strain and ferroelectric-antiferrodistortive coupling at the film surface vary for the strain mediated transition sequence and this could offer a route for experimental observation of the morphologies. Remarkably, we identify a new nanobubble domain morphology that is stable in the high-temperature regime for compressively strained PbTiO3. We demonstrate that the formation mechanism of the nanobubble domains morphology is related to the wandering of flux closure domain walls, which we characterise using the hypertoroidal moment. These results provide insight into the local behaviour and dynamics of ferroelectric domains in ultrathin films to open up potential applications for bubble domains in new technologies and pathways to control and exploit novel phenomena in dimensionally constrained materials.

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“…In these ferrites, moreover, the charge and spin degrees of freedom of electrons can be controlled simultaneously, because they have ferrimagnetic order and thus may have non-zero magnetization. Recently, two primary non-polar distortions like tilting and rotation of oxygen octahedra driven by electronic factors (i.e., Jahn-Teller effects) were found to induce the breaking of inversion symmetry and produce a large ferroelectric polarization in the new class of double perovskites AA ′ BB ′ O 6 ; SrTiO 3 /PbTiO 3 superlattice [28], NaLaMnWO 6 [9,29] with a very large polarization of about 16 µC/cm 2 , and Ca 3 Mn 2 O 7 [10] are typical compounds belonged to this materials class. These materials have weak ferromagnetism and thus a significant ME coupling is expected.…”

mentioning

confidence: 99%

First-principles study of ferroelectricity induced by p–d hybridization in ferrimagnetic NiFe 2 O 4

Jong¹,

Yu²,

Park³

et al. 2016

Physics Letters A

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We investigate the ferrimagnetism and ferroelectricity of bulk NiFe2O4 with tetragonal P 4122 symmetry by means of density functional calculations using generalized gradient approximation + Hubbard U approach. Special attention is paid to finding the most energetically favorable configuration on magnetic ordering and further calculating the reliable spontaneous electric polarization. With the fully optimized crystalline structure of the most stable configuration, the spontaneous polarization is obtained to be 23 µC/cm 2 along the z direction, which originates from the hybridization between the 3d states of the Fe 3+ cation and the 2p states of oxygen induced by Jahn-Teller effect.PACS numbers: 41.20. Gz, 75.85.+t,Magnetic ferroelectrics that possess ferroelectricity together with some form of magnetic order like ferromagnetic, antiferromagnetic, or ferrimagnetic property in the same crystalline phase have attracted much interest due to their fundamental physics and a great promise for applications in future information technology [2][3][4][5][6][7][8]. In particular, improper multiferroics in which a ferroelectric polarization is induced by electronic correlation effects such as non-centrosymmetric spin, charge, and orbital ordering, is currently under intensive study [9][10][11][12]. This is related to the suggestion that a magneto-electric (ME) coupling in improper multiferroics is expected to be stronger than in proper case, because both dipolar and magnetic orderings share the same physical origin and occur at the same temperature [9].In the early days of searching improper multiferroics, spin ordering was accepted to be a main driving force for the manifestation of ferroelectric polarization; examples include rare earth manganites RMnO 3 [13][14][15][16] [10] are typical compounds belonged to this materials class. These materials have weak ferromagnetism and thus a significant ME coupling is expected. Despite the great progress in the field of improper multiferroics, the effort to find new mechanism and design new materials is being continued.In this letter, we present that spinel-type nickel ferrite NiFe 2 O 4 (NFO) is a promising candidate for improper multiferroics with finite magnetization and considerably large polarization, based on the first-principles density functional theory (DFT) calculations. In fact, spinels exhibit several unusual features including magnetoelectricity and multiferroicity [9]. From the experiment, it was established that the bulk NFO shows soft ferrimagnetic ordering below relatively high transition temperature of 850 K with a magnetization of 2 µ B per formula unit (f.u.) [30]. In the recent experiment [31], moreover, high dielectric permitivity was observed in NFO nanoparticles to be ranged from 60 to 600 at different frequencies and temperatures. This is comparable with the conventional ferroelectrics and therefore implies the presence of spontaneous polarization in the bulk NFO. However, the ferroelectricity of bulk NFO has neither been calculated nor measured yet, though ...

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Improper ferroelectricity in perovskite oxide artificial superlattices

Cited by 845 publications

References 34 publications

Negative capacitance in multidomain ferroelectric superlattices

Negative capacitance in multidomain ferroelectric superlattices

Novel high-temperature ferroelectric domain morphology in PbTiO₃ ultrathin films

First-principles study of ferroelectricity induced by p–d hybridization in ferrimagnetic NiFe 2 O 4

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Improper ferroelectricity in perovskite oxide artificial superlattices

Cited by 845 publications

References 34 publications

Negative capacitance in multidomain ferroelectric superlattices

Negative capacitance in multidomain ferroelectric superlattices

Novel high-temperature ferroelectric domain morphology in PbTiO3 ultrathin films

First-principles study of ferroelectricity induced by p–d hybridization in ferrimagnetic NiFe 2 O 4

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Novel high-temperature ferroelectric domain morphology in PbTiO₃ ultrathin films