Ferrotoroidic structures: polar flux-closure, vortices and skyrmions
Lead Research Organisation:
University of Warwick
Department Name: Physics
Abstract
The impressive amount of data produced daily by modern society requires more efficient information storage. Current capabilities need not only to be increased to meet demand, but also to be fundamentally changed to offer better density, power consumption, access speed and time stability. Existing data encoding is based on switching of ferroic order parameters such as magnetisation and polarisation that exist in ferromagnetic and ferroelectric materials, respectively. The effect of finite size sets a fundamental limit of the data density and retention that is being rapidly approached by current technologies. Therefore, there is critical need for novel data encoding mechanisms. One alternative is offered by ferrotoroidic structures that show multiple order parameters, related to properties such as chirality and winding number, which can be used to encode extra information. Not only do these additional parameters multiply the achievable information density, but they are predicted to exist exactly at the characteristic length where classical ferroic parameters are no longer effective for data encoding. Thus, ferrotoroidics provide an alternative way to overcome the limits of classical data storage.
Ferrotoroidic structures have been theoretically predicted but only very recently have they been experimentally observed. Besides the enormous application potential, especially in non-volatile memories, these exotic polar entities may require new physics to be fully understood. The present research aims to experimentally elucidate the origin of the ferrotoroidic structures through a comprehensive program of work. By understanding this complex phenomena, we will gain control of and tune the ferrotoroidicity in terms of density, chirality and spatial positioning.
We are especially targeting oxide polar ferrotoroidics in which the reorientation of the spontaneous polarization is a result of atomic displacement. For this reason, transmission electron microscopy is the technique of choice to determine the oxide properties at nanoscopic scale by measuring the displacement of atoms relative to each other. In-situ electron microscopy will provide real time information to investigate the effective interactions between electric fields and polar entities as well as potentially switch the toroidal moment chirality to demonstrate data encoding.
Ferrotoroidic structures have been theoretically predicted but only very recently have they been experimentally observed. Besides the enormous application potential, especially in non-volatile memories, these exotic polar entities may require new physics to be fully understood. The present research aims to experimentally elucidate the origin of the ferrotoroidic structures through a comprehensive program of work. By understanding this complex phenomena, we will gain control of and tune the ferrotoroidicity in terms of density, chirality and spatial positioning.
We are especially targeting oxide polar ferrotoroidics in which the reorientation of the spontaneous polarization is a result of atomic displacement. For this reason, transmission electron microscopy is the technique of choice to determine the oxide properties at nanoscopic scale by measuring the displacement of atoms relative to each other. In-situ electron microscopy will provide real time information to investigate the effective interactions between electric fields and polar entities as well as potentially switch the toroidal moment chirality to demonstrate data encoding.
Planned Impact
Ferrotoroidic structures have become a very hot topic of research, having potential technological applications whilst also challenging fundamental theories. We expect to achieve an immediate impact by publishing our results in high impact broad interest and focused reviewed journals. The interplay between structure, strain, electric and magnetic field results in novel ferroic materials showing different ferroic order parameters and topologically protected states. This will lead to new science, developing the field of functional oxide materials in particular.
In addition to the significant scientific impact in the short to medium term, the research program will develop trained research personnel to fill positions available in Universities in the high technology areas such as thin film growth, micro- and nano-fabrication, transmission electron microscopy, etc., all in high demand in the UK. There will also be benefits in terms of this project's impact on the ability of the investigators of obtain funding for further research from European and US funding agencies, as well as to build collaborative links with new partners.
We will organise an international workshop focused on topologically protected state in ferroelectric materials that will ensure engagement with the scientific community and facilitate the establishment of new collaborations in the area. Outreach activities aimed particularly at local school pupils will be organize in collaboration with the Warwick Ogden Trust Teaching Fellow.
Our Regional Development Agency, Advantage West Midlands (and the European Regional Development Fund) funded in the past the Science City Initiative between Universities of Warwick and Birmingham for research into Advanced Materials. The aim of this initiative was to establish the region as an international competitor in materials Physics, undertaking world-class research in the development and characterisation of new materials for applications in a diverse range of industries. The present proposal will enhance the present capabilities in the area of Advanced Materials and stimulate research that will be beneficial to local, UK and European companies.
In addition to the significant scientific impact in the short to medium term, the research program will develop trained research personnel to fill positions available in Universities in the high technology areas such as thin film growth, micro- and nano-fabrication, transmission electron microscopy, etc., all in high demand in the UK. There will also be benefits in terms of this project's impact on the ability of the investigators of obtain funding for further research from European and US funding agencies, as well as to build collaborative links with new partners.
We will organise an international workshop focused on topologically protected state in ferroelectric materials that will ensure engagement with the scientific community and facilitate the establishment of new collaborations in the area. Outreach activities aimed particularly at local school pupils will be organize in collaboration with the Warwick Ogden Trust Teaching Fellow.
Our Regional Development Agency, Advantage West Midlands (and the European Regional Development Fund) funded in the past the Science City Initiative between Universities of Warwick and Birmingham for research into Advanced Materials. The aim of this initiative was to establish the region as an international competitor in materials Physics, undertaking world-class research in the development and characterisation of new materials for applications in a diverse range of industries. The present proposal will enhance the present capabilities in the area of Advanced Materials and stimulate research that will be beneficial to local, UK and European companies.
Organisations
Publications
Apachitei G
(2017)
Antiferroelectric Tunnel Junctions
in Advanced Electronic Materials
Dong C
(2020)
B ? N Unit Enables n-Doping of Conjugated Polymers for Thermoelectric Application.
in ACS applied materials & interfaces
Dong W
(2020)
Emergent Antipolar Phase in BiFeO3-La0.7Sr0.3MnO3 Superlattice.
in Nano letters
Gott JA
(2019)
Defect Dynamics in Self-Catalyzed III-V Semiconductor Nanowires.
in Nano letters
Gruverman A
(2019)
Piezoresponse force microscopy and nanoferroic phenomena.
in Nature communications
Heo Y
(2022)
Boosting Piezoelectricity under Illumination via the Bulk Photovoltaic Effect and the Schottky Barrier Effect in BiFeO3.
in Advanced materials (Deerfield Beach, Fla.)
Himcinschi C
(2019)
Ferroelastic domain identification in BiFeO3 crystals using Raman spectroscopy
in Scientific Reports
Hrib LM
(2017)
Magnetocapacitance in La0.7Sr0.3MnO3/Pb(Zr0.2Ti0.8)O3/La0.7Sr0.3MnO3 multiferroic heterostructures.
in Scientific reports
Hussein HEM
(2018)
Tracking Metal Electrodeposition Dynamics from Nucleation and Growth of a Single Atom to a Crystalline Nanoparticle.
in ACS nano
J.J.P. Peters
(2017)
Vortex-antivortex topological structures in multiferroic tunnel junctions
Kwamen C
(2019)
Time-resolved X-ray diffraction study of the structural dynamics in an epitaxial ferroelectric thin Pb(Zr0.2Ti0.8)O3 film induced by sub-coercive fields
in Applied Physics Letters
Luo Z
(2019)
Dissolvable Memristors for Physically Transient Neuromorphic Computing Applications
in ACS Applied Electronic Materials
Luo ZD
(2021)
Emerging Opportunities for 2D Semiconductor/Ferroelectric Transistor-Structure Devices.
in Advanced materials (Deerfield Beach, Fla.)
Luo ZD
(2019)
Light-Controlled Nanoscopic Writing of Electronic Memories Using the Tip-Enhanced Bulk Photovoltaic Effect.
in ACS applied materials & interfaces
Luo ZD
(2019)
Flexible Memristors Based on Single-Crystalline Ferroelectric Tunnel Junctions.
in ACS applied materials & interfaces
Luo Zhengdong
(2019)
Magnetoelectric and optoelectric effects in ferroelectric tunnel junctions
Mingmin Yang
(2018)
Photoelectric processes in ferroelectric/multiferroic materials
Peters J
(2020)
Structural and photoelectric properties of tensile strained BiFeO 3
in Physical Review Materials
Peters J
(2023)
Interlacing in Atomic Resolution Scanning Transmission Electron Microscopy
in Microscopy and Microanalysis
Peters JJP
(2021)
A Fast Frozen Phonon Algorithm Using Mixed Static Potentials.
in Ultramicroscopy
Peters JJP
(2020)
Polarization Screening Mechanisms at La0.7Sr0.3MnO3-PbTiO3 Interfaces.
in ACS applied materials & interfaces
Peters JJP
(2019)
Quantitative High-Dynamic-Range Electron Diffraction of Polar Nanodomains in Pb2 ScTaO6.
in Advanced materials (Deerfield Beach, Fla.)
Rusu D
(2022)
Ferroelectric incommensurate spin crystals
in Nature
Seddon S
(2021)
Real-space observation of ferroelectrically induced magnetic spin crystal in SrRuO3
in Nature Communications
Tian G
(2019)
Topological domain states and magnetoelectric properties in multiferroic nanostructures
in National Science Review
Valleti S
(2022)
Unsupervised learning of ferroic variants from atomically resolved STEM images
in AIP Advances
Yang MM
(2019)
Strain-gradient mediated local conduction in strained bismuth ferrite films.
in Nature communications
Yang MM
(2020)
Piezoelectric and pyroelectric effects induced by interface polar symmetry.
in Nature
Yang MM
(2018)
Flexo-photovoltaic effect.
in Science (New York, N.Y.)
Description | Significant outcome is revealed in the field of exotic phenomena in size-confined multiferroic systems, including topological domain states such as vortices, centre domains, and skyrmion and bubble domains. It has then been shown that polarisation induces interfacial breaking symmetry and polar phase in several neighbouring materials. The results are astonishing. For instance, polar ferromagnetic manganite and ruthenate layers are induced over significant thickness from their interface with ferroelectrics. This change the general picture of interfacial magnetoelectric effects based interface Dzyaloshinskii-Moriya interaction (iDMI). We have shown that not only skyrmions are induced in the ferromagnetic layers, but also more exotic ice spin phases found only in a handful of systems so far. Important influence this metal-ferroelectric interface, especially of the effective electronic properties including density of states, was shown in antiferroelectric and biferroic tunnel junctions. A novel phase has been discovered in metal-ferroelectric-metal heterostructures with the thickness of ferroelectric layer in a narrow region of 8-12 unit cell. The ferroelectric arranges in a so-called incommensurate spin crystal phase mimicking the similar phase found in ferromagnetic materials under iDMI. This ferroelectric phase is the result of a newly discovered interaction namely electric DMI which is the analogous if magnetic DMI. The result is a highly ordered polar phase in which an initial periodic vortex state is modulated by a second periodicity normal on the direction of the first vortex periodicity. The result is cycloidally-modulated vortex phase. Strain was discovered as playing a significant role in both electronic properties and domain structure. An emergent antipolar phase has been discovered that it is forming in bismuth ferrite - maganite superlattices. The emergent phase is characterized by an arrangement of a two unit cell thick lamella-like structure featuring antiparallel polarization, resulting an antiferroelectric-like structure typically associated with a morphotropic phase transition. We have also shown that in PbTiO3 (PTO)-based multiferroic tunnel junctions (MFTJs) the ferroelectric domain pattern for PTO at a thickness of 9 unit cells (u.c.) is generally classic antiparallel (180°) with Ising type domain walls decorated with coupled clockwise and anti-clockwise vortices. For 6 u.c., a peculiar domain pattern with curling flux-closure type structures and incommensurate phase was observed. For only 3-u.c.-thick PTO films, domain structure is widely suppressed with polarization pointing out of plane and remanent domain structure. |
Exploitation Route | The polar vortices can in principle be at the basis of novel non-volatilel memory devices in which the information is encoded in the toroidal moment or chirality of the vortices instead of polarisation, is in the classical ferroelectric memories (FeRAMs), or magnetisation in MRAMs. |
Sectors | Digital/Communication/Information Technologies (including Software),Education,Electronics |
Description | SiliNano |
Geographic Reach | Europe |
Policy Influence Type | Participation in a guidance/advisory committee |
URL | https://www.sili-nano.de/advisory-board.html |
Description | Contributed talk XXI International Workshop on Physics of Semiconductor Devices (IWPSD 2021) |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Contributed talk by Bhera Ram Tak, MM Yang, Vinay Gupta, YH Chu, Rajendra Singh, and Marin Alexe, "Flexible deep UV photodetectors on ß-Ga2O3 epitaxy", XXI International Workshop on Physics of Semiconductor Devices (IWPSD 2021) held at Indian Institute of Technology Delhi during December 14-17, 2021 |
Year(s) Of Engagement Activity | 2021 |
Description | Interfacial coupling in BFO/LSMO superlattices |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Contributed talk at IEEE ISAF-EMF-ICE-IWPM-PFM, EPFL, Switzerland, July 2019 presented by Wen Dong |
Year(s) Of Engagement Activity | 2019 |
URL | https://ieee-uffc.org/news/2019-ieee-isaf-lausanne-july-2019/ |
Description | Invited Talk 6th Workshop on Materials Physics 2021 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Invited talk to 6th Workshop on Materials Physics. Latest results on domain walls, vortices, and topological structures were reports and received a massive interest. |
Year(s) Of Engagement Activity | 2021 |
URL | https://infim.ro/event/6th-edition-of-the-international-workshop-of-materials-physics-first-announce... |
Description | Invited Talk at at Young scientist PACE conference, Luxembourg |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Postgraduate students |
Results and Impact | Invited talk at a conference organised by and for young postgraduate students. |
Year(s) Of Engagement Activity | 2022 |
Description | Invited Tlak Halle 2021 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Professional Practitioners |
Results and Impact | Invited talk the Martin Luther University Halle, Germany |
Year(s) Of Engagement Activity | 2021 |
Description | Loughborough University |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Postgraduate students |
Results and Impact | scientific talk presenting latest achievement at Warwick. |
Year(s) Of Engagement Activity | 2021,2022 |
Description | Organisation of conference |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Organisation of the conference of the European Meeting on Ferroelectricity (EMF) part of the IEEE International Symposium on the Applications of Ferroelectrics (ISAF) was held at the Swiss Tech Convention Center near the EPFL in Lausanne, Switzerland, from July 14th to 19th, 2019 within the joint Conference, "F2cp2 2019", that united ISAF with several other international and European symposia : -International Conference on Electroceramics (ICE); -European Meeting on Ferroelectricity (EMF); -International Workshop on PiezoMEMS (IWPM); -Piezoresponse Force Microscopy Workshop (PFM). |
Year(s) Of Engagement Activity | 2019 |
URL | https://ieee-uffc.org/news/2019-ieee-isaf-lausanne-july-2019/ |
Description | Plenary lecture ISAF2021 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | This was a plenary lecture to the most important conference of the field of ferroelectrics. |
Year(s) Of Engagement Activity | 2021 |
URL | https://isaf-isif-pfm2021.org |
Description | Polar exploration: Quantitative polarisation measurements in ferroelectric films |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Postgraduate students |
Results and Impact | Contributed talk to Oxford Microscopy (ATOM) XV workshop (24th Sep) presented by Jonathan JP Peters. |
Year(s) Of Engagement Activity | 2020 |
Description | Polar exploration: Quantitative polarisation measurements in ferroelectric films |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Seminar to Trinity College Dublin presented by Jonathan JP Peters. |
Year(s) Of Engagement Activity | 2020 |
Description | Property Optimization of Novel Dielectric Functional Materials and Devices |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Seminar at Yunnan University, Kunming, Yunnan, China, November 2020 presented by Wen Dong |
Year(s) Of Engagement Activity | 2020 |
Description | Stabilising novel ferroic phases though interface engineering: The role of the TEM |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Contributed presentation to at Microscopy Society of Ireland Symposium 2021 (7th January) |
Year(s) Of Engagement Activity | 2018,2021 |
Description | TU Dresden seminar |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Postgraduate students |
Results and Impact | Talk given by Samuel Seddon within the regular departmental seminar at TU Dresden. Attended by >50 people including undergraduate and postgraduate students. The latest results regarding the low-temperature AFMN investigations have been reported. |
Year(s) Of Engagement Activity | 2022 |
Description | Talk APS March meeting 2021 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Talk presented by Sam Seddon et al., Real-space Observation of Ferroelectrically Induced Magnetic Spin Crystal in SrRuO3, at the APS march meeting 2021 |
Year(s) Of Engagement Activity | 2021 |
URL | https://meetings.aps.org/Meeting/MAR21/Session/J40.8 |
Description | Talk attcube Munich 2022 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Professional Practitioners |
Results and Impact | Talk given by Samuel Seddon to attcube GmbH. Attended by >20 people mostly professional. The latest results regarding the low-temperature AFMN investigations have been reported. |
Year(s) Of Engagement Activity | 2022 |