Anti-ferroelectric materials for non-volatile memory applications
Lead Research Organisation:
University of Portsmouth
Department Name: Sch of Earth & Environmental Sciences
Abstract
The worldwide demand for digital data storage is increasing exponentially. IBM estimates that 2.5 quintillion of digital data bytes are produced every day on Earth (2.5 x 1018 bytes = 2.5 Exabytes = 2.5 billion Gigabytes). This huge digital data storage demand has two consequences:
a) the increased power consumption of data storage servers;
b) the perpetual need to develop data storage technologies that meet the increasing demand at reduced cost and power consumption.
These issues have prompted the acceleration of research into solid-state memories, which are fast replacing traditional magnetic hard disc drives in almost all consumer electronics and portable devices.
In Dec. 2016 and Jan. 2017, the principal investigator (PI) of this travel grant and his co-investigator from Iowa State University, proposed and demonstrated, for the first time, a novel solid-state memory effect in bulk anti-ferroelectric ceramic materials [1-3]. Although this is a very promising discovery, the authors pointed out a few issues that required further investigation, including a relaxation process that significantly limited the signal recovered from a memory cell. In addition, it was acknowledged that the effect was observed in bulk anti-ferroelectric materials, while solid-state memory chips are based on thin films.
This modest EPSRC overseas travel grant (< £15k), seeks to swiftly redress these issues by facilitating five weeks travel to three overseas institutions, in two countries, in order to perform specialized experiments on anti-ferroelectric materials and to acquire key skills that will advance our understanding of anti-ferroelectric materials and potentially accelerate the commercialization of this research. By working with leading researchers in the field of data storage technologies at Western Digital (WD) - California, physics of anti-ferroelectric materials at Iowa State University (ISU) and experts in Mossbauer Spectroscopy at the National Institute of Materials Physics (NIMP) in Bucharest, the PI will have the opportunity to study relaxation processes and memory effect in anti-ferroelectric thin films. In addition, the PI will acquire valuable new experimental skills such as: fabrication of anti-ferroelectric materials and their domains imaging using in-situ Transmission Electron Microscopy (ISU), device architecture / solid state memory cell testing (WD) and Mossbauer Spectroscopy (NIMP). This is an excellent value for money low-risk / high-gain EPSRC travel grant, with huge potential for academic, societal and economic impacts.
[1]. M. Vopson, X. Tan, 4-state anti-ferroelectric random access memory, Electron Device Letters (2016).
[2]. M. Vopson, G. Caruntu, X. Tan, Polarization reversal and memory effect in anti-ferroelectric materials, Scripta Materialia vol. 128, 61-64 (2017).
[3]. M. Vopson, X. Tan, Nonequilibrium polarization dynamics in antiferroelectrics, Physical Review B 96 (1), 014104 (2017)
a) the increased power consumption of data storage servers;
b) the perpetual need to develop data storage technologies that meet the increasing demand at reduced cost and power consumption.
These issues have prompted the acceleration of research into solid-state memories, which are fast replacing traditional magnetic hard disc drives in almost all consumer electronics and portable devices.
In Dec. 2016 and Jan. 2017, the principal investigator (PI) of this travel grant and his co-investigator from Iowa State University, proposed and demonstrated, for the first time, a novel solid-state memory effect in bulk anti-ferroelectric ceramic materials [1-3]. Although this is a very promising discovery, the authors pointed out a few issues that required further investigation, including a relaxation process that significantly limited the signal recovered from a memory cell. In addition, it was acknowledged that the effect was observed in bulk anti-ferroelectric materials, while solid-state memory chips are based on thin films.
This modest EPSRC overseas travel grant (< £15k), seeks to swiftly redress these issues by facilitating five weeks travel to three overseas institutions, in two countries, in order to perform specialized experiments on anti-ferroelectric materials and to acquire key skills that will advance our understanding of anti-ferroelectric materials and potentially accelerate the commercialization of this research. By working with leading researchers in the field of data storage technologies at Western Digital (WD) - California, physics of anti-ferroelectric materials at Iowa State University (ISU) and experts in Mossbauer Spectroscopy at the National Institute of Materials Physics (NIMP) in Bucharest, the PI will have the opportunity to study relaxation processes and memory effect in anti-ferroelectric thin films. In addition, the PI will acquire valuable new experimental skills such as: fabrication of anti-ferroelectric materials and their domains imaging using in-situ Transmission Electron Microscopy (ISU), device architecture / solid state memory cell testing (WD) and Mossbauer Spectroscopy (NIMP). This is an excellent value for money low-risk / high-gain EPSRC travel grant, with huge potential for academic, societal and economic impacts.
[1]. M. Vopson, X. Tan, 4-state anti-ferroelectric random access memory, Electron Device Letters (2016).
[2]. M. Vopson, G. Caruntu, X. Tan, Polarization reversal and memory effect in anti-ferroelectric materials, Scripta Materialia vol. 128, 61-64 (2017).
[3]. M. Vopson, X. Tan, Nonequilibrium polarization dynamics in antiferroelectrics, Physical Review B 96 (1), 014104 (2017)
Planned Impact
The main topic of this project revolves around the potential use of anti-ferroelectric materials to store digital information. The effect is already confirmed in bulk anti-ferroelectrics, and the PI seeks to expand his research into thin films.
The confirmation of a 4-state memory effect in anti-ferroelectric thin films is a paradigm shift in non-volatile solid-state memories. The proposed new RAM memory device, AFRAM, does not exist at present and it will combine the device architecture of existing FRAM to create a novel 4-state non-volatile memory. The successful implementation of AFRAM potentially will have huge economic and societal impact.
In particular, the success of the project has the potential to impact the whole UK advanced manufacturing economy and the Global multi-billion $ non-volatile memory chips industry. FRAM chips have been mass produced since 1995 by Fujitsu. So far 10 billion FRAM chips have been commercialized globally and the demand is projected to increase significantly. The economic and societal impacts of potentially replacing FRAM with AFRAM are therefore huge. Companies with a strong portfolio of data storage technologies such as Fujitsu, Toshiba, and Seagate have a well-established presence in the UK with thousands of jobs in production and R&D, and they would be immediate beneficiaries of this research.
To maximize the industrial impact, the PI has already established industrial links with Western Digital, a global data storage company based in California. The importance of solid state memories is best emphasised by the recent diversification of Western Digital from traditional magnetic hard disc drive storage to solid state memories by acquiring SanDisk Corporation. Under this EPSRC travel grant, the PI will meet the R&D solid state memory team at Western Digital to discuss the new AFRAM technology. The PI has already been invited to deliver, during his visit, one lecture at Western Digital and one lecture at the IEEE Magnetics Society Chapter in San Jose, California.
The project has also an environmental impact dimension as it can facilitate the introduction of more energy efficient AFRAM memory chips that retain the benefits of FRAM, but require 100x less power in comparison to competitor technologies. This is especially of importance to portable electronics where battery life time is essential.
Besides the clear academic impacts detailed in a separate section, the strongest points of this project are its potential economic, societal and environmental impacts with key beneficiaries in high-tech industry, data storage, advanced manufacturing and development of scientific measurements. EPSRC funding of this modest grant is therefore low-risk / high-gain.
The confirmation of a 4-state memory effect in anti-ferroelectric thin films is a paradigm shift in non-volatile solid-state memories. The proposed new RAM memory device, AFRAM, does not exist at present and it will combine the device architecture of existing FRAM to create a novel 4-state non-volatile memory. The successful implementation of AFRAM potentially will have huge economic and societal impact.
In particular, the success of the project has the potential to impact the whole UK advanced manufacturing economy and the Global multi-billion $ non-volatile memory chips industry. FRAM chips have been mass produced since 1995 by Fujitsu. So far 10 billion FRAM chips have been commercialized globally and the demand is projected to increase significantly. The economic and societal impacts of potentially replacing FRAM with AFRAM are therefore huge. Companies with a strong portfolio of data storage technologies such as Fujitsu, Toshiba, and Seagate have a well-established presence in the UK with thousands of jobs in production and R&D, and they would be immediate beneficiaries of this research.
To maximize the industrial impact, the PI has already established industrial links with Western Digital, a global data storage company based in California. The importance of solid state memories is best emphasised by the recent diversification of Western Digital from traditional magnetic hard disc drive storage to solid state memories by acquiring SanDisk Corporation. Under this EPSRC travel grant, the PI will meet the R&D solid state memory team at Western Digital to discuss the new AFRAM technology. The PI has already been invited to deliver, during his visit, one lecture at Western Digital and one lecture at the IEEE Magnetics Society Chapter in San Jose, California.
The project has also an environmental impact dimension as it can facilitate the introduction of more energy efficient AFRAM memory chips that retain the benefits of FRAM, but require 100x less power in comparison to competitor technologies. This is especially of importance to portable electronics where battery life time is essential.
Besides the clear academic impacts detailed in a separate section, the strongest points of this project are its potential economic, societal and environmental impacts with key beneficiaries in high-tech industry, data storage, advanced manufacturing and development of scientific measurements. EPSRC funding of this modest grant is therefore low-risk / high-gain.
Organisations
- University of Portsmouth (Lead Research Organisation)
- Materials Physics Center (CSIC-UPV/EHU) (Collaboration)
- National Institute of Materials Physics Magurele-Bucharest (Collaboration)
- National Institute of Materials Physics (Project Partner)
- Iowa State University (Project Partner)
- Western Digital (United States) (Project Partner)
People |
ORCID iD |
| Melvin Vopson (Principal Investigator) |
Publications
Vopson M
(2019)
Sub-lattice polarization states in anti-ferroelectrics and their relaxation process
in Current Applied Physics
Vopson M
(2019)
The mass-energy-information equivalence principle
in AIP Advances
Vopson M
(2018)
A new method to study ferroelectrics using the remanent Henkel plots
in Journal of Physics D: Applied Physics
| Description | Key Findings 1) We determined that the relaxation process of the quasi-remanent polarization states in anti-ferroelectrics, also known as memory states, is in fact a structural relaxation process consistent with a phase transition from quasi-tetragonal perovskite in 0V relaxed anti-ferroelectric state to rhombohedral distortion in ferroelectric state under saturating applied voltages. These studies were done at UK Diamond Light Source facility using unique in-situ electrically activated time-resolved Synchrotron X-ray powder diffraction (SXPD). Hence the observed quasi-remanent polarization relaxation processes are due to the fact that tetragonal to rhombohedral distortion does not occur at the applied voltage required for the memory "read-out" operation and the quasi-tetragonal symmetry restored after the data "write" operation is preserved. This is an important and unexpected result, addressing Objectives 1, 2 of the current Research Travel Grant. The implications are that anti-ferroelectrics are more feasible for multi-state dynamic random access memories (DRAM), while their application to non-volatile memories requires development of more sophisticated "read-out" protocols, possibly involving dc electrical biasing during the read-out operation. 2) Room temperature 119Sn Mössbauer Spectroscopy Mössbauer of the PNZST anti-ferroelectric ceramic in powder form indicates the lack of quadrupole splitting, or magnetic hyperfine field present at the Sn sites, while the isomer shift is very close to zero (Objective 2). Measurements on anti-ferroelectric samples with slightly different Ti concentration resulted in similar results. The results indicate an oxidation state of IV for the Sn ions, with the spectrum showing no trace for any other different electron configuration of Sn. The rather narrow spectral line (i.e. 1.28 mm/s at half-width), also suggests a lack of sensible crystal field distortion at the Sn site, implying that their contribution to the spontaneous polarization of the two sublattices is negligible. 3) Extended memory retention measurements at four different waiting times were performed at UoP and they revealed a strong relaxation process (Objective 1). Measurements were performed on four anti-ferroelectric Pb0.99Nb0.02[(Zr0.57Sn0.43)1-yTiy]0.98O3 (PNZST) ceramics produced with variable Ti doping (y =0.05, 0.055, 0.061 and 0.064). The results showed a slight variation of the reversal process with the Ti doping and the relaxation effects were reconfirmed. 4) Experimental development of new measurement techniques for polar and anti-polar materials to characterize complex intrinsic interactions not visible in standard polarization reversal measurements. In this project it has been demonstrated that Henkel and delta P plots, derived from the Wohlfarth relation in magnetics can be extended to polar systems. It has been shown, for the first time, that experimental measurement of the dc depolarisation and isothermal remanent polarization curves, as well as the construction of the Henkel plots, delta P plots and polarization switching field distribution for ferroelectrics, are possible. These measurements have been tested only on ferroelectrics and the next step is to apply these techniques to anti-ferroelectrics. Overview of the Travel Grant The principal investigator (PI) of this 5 weeks EPSRC overseas travel grant (< £15k) proposed and demonstrated recently a novel solid-state memory effect in bulk anti-ferroelectric ceramic materials. Although this was a very promising discovery, the research was far from settled and a few issues required further investigation, including a polarization relaxation process that significantly limited the signal recovered from a memory cell and the fact that the effect was demonstrated in bulk anti-ferroelectric materials, while solid-state memory chips are based on thin films. The current travel grant facilitated the PIs travel to three overseas institutions, in two countries, in order to perform specialized experiments and to acquire key skills that will advance our understanding of anti-ferroelectric materials. The first visit was Western Digital in San Jose, California where the PI met R&D engineers in digital data storage and discussed the current scientific issues and technical challenges of bringing this technology to the market (Objective 4). The PI also delivered a lecture at Western Digital on his current research on anti-ferroelectric memories and an invited talk at IEEE Magnetics Society, Santa Clara Chapter, San Jose, on 17 July 2018 on the topic of applications of multiferroic materials to data storage technologies. The second visit was at the National Institute of Materials Physics (NIMP) in Bucharest, where the PI has received training on Mossbauer Spectroscopy technique (Objective 2). for materials characterization including data analysis and fitting from Prof. Kuncser. The training was mostly on Fe57 transmission and surface Conversion Electron Mössbauer Spectroscopy (CEMS), while the measurements of anti-ferroelectric materials required Sn119 Mössbauer Spectroscopy since our anti-ferroelectric compounds contain Sn Mössbauer active element rather than Fe. These measurements were not possible at NIMP due to the radioactive source being depleted, so the tests were performed at Department of Electricity and Electronics, UPV/EHU, Spain. The third visit was at Department of Materials Science, Iowa State University (ISU) where the PI acquire valuable new experimental skills such as fabrication of anti-ferroelectric materials and their domains imaging using in-situ Transmission Electron Microscopy (ISU), addressing Objective 3. The PI also delivered two lectures. One to the Research group of his host academic, Prof. Xiaoli Tan, and second lecture was delivered on 8th of November 2018 to the Department of Materials Science, ISU on the topic: Ferroelectric and Anti-ferroelectric Oxides for Memories. Articles output M.M. Vopson, X. Tan, E. Namvar, M. Belusky, S.P. Thompson, V. Kuncser, F. Plazaola, I. Unzueta, C.C. Tang, Sub-lattice polarization states in anti-ferroelectrics and their relaxation process, Current Applied Physics (2019) - under review. M. Vopson, A new method to study ferroelectrics using the remanent Henkel plots, J. Phys. D: Appl. Phys. 51 (20), 205304 (2018). |
| Exploitation Route | Our studies indicate that the anti-ferroelectric solids are promising candidates for the development of digital memories. However, the application of anti-ferroelectrics to non-volatile memories is questionable because of the observed relaxation processes. This suggests the possibility of using anti-ferroelectrics at least for multi-state dynamic random access memories (DRAM). Our time-resolved synchrotron studies indicate that the observed relaxation process in the anti-ferroelectrics is related to a structural relaxation due to the fact that the activation voltages required for the "read-out" process are not sufficiently large to induce the rhombohedral distortion, so the quasi-remanent polarization values are far lower than those observed on PE hysteresis loops. These studies might be taken forward by key Industrial and academic players including our partners at Western Digital to hopefully stimulate further research into anti-ferroelectric memories including development of better memory "read-out" protocols to minimize the observed memory relaxation process. The successful measurement of the dc depolarisation and isothermal remanent polarization curves, as well as the construction of the Henkel plots, delta P plots and polarization switching field distribution reported here are expected to generate significant impact as they could be invaluable tools for future studies of depolarising effects, relaxors, defects in ferroelectrics, ferroelectric hetero-structures, geometrical, size, topological and thickness effects in ferroelectrics, surface and interfaces effects, dead layer effects and even other polar / anti-polar ordered systems such as anti-ferroelectrics and multiferroics. |
| Sectors | Digital/Communication/Information Technologies (including Software),Electronics,Other |
| Description | In-situ synchrotron studies of anti-ferroelectric materials for digital data storage |
| Amount | £38,376 (GBP) |
| Funding ID | EE18495 |
| Organisation | Diamond Light Source |
| Sector | Private |
| Country | United Kingdom |
| Start | 07/2018 |
| End | 08/2018 |
| Title | A new method to study polar and anti-polar materials using the remanent Henkel and delta-P plots |
| Description | Experimental characterization of polar dielectrics is essential to advance our understanding of their polarization dynamics and to further improve their commercial applicability. The main experimental measurement tools involving polarization hysteresis measurements, dielectric constant measurements, piezo-displacement measurements and various microscopy or structural measurements under various external fields, stress, time and temperature conditions are indeed very valuable. However, complex intrinsic interactions are not visible in these standard measurements and more specialized experimental tools are required. For over half a century, interactions in magnetic systems have been successfully characterized using experimental curves constructed from dc demagnetisation and isothermal remanent magnetization known as Henkel and delta M plots, derived from the Wohlfarth relation. This new method here has shown, for the first time, that the same experimental techniques could be applied to the study of polar dielectric systems, and the successful measurement of the dc depolarisation and isothermal remanent polarization curves, as well as the construction of the Henkel plots, delta P plots and polarization switching field distribution for ferroelectrics, have been reported. These measurements are extremely beneficial as an additional experimental tool for polar and anti-polar dielectrics measurements. |
| Type Of Material | Improvements to research infrastructure |
| Year Produced | 2018 |
| Provided To Others? | Yes |
| Impact | A new experimental measurement technique for polar and anti-polar materials to characterize complex intrinsic interactions not visible in standard polarization reversal measurements. The proposed measurements are expected to generate significant impact as they could be invaluable tools for future studies of depolarising effects, relaxors, defects in ferroelectrics, ferroelectric hetero-structures, geometrical, size, topological and thickness effects in ferroelectrics, surface and interfaces effects, dead layer effects [and even other polar ordered systems such as anti-ferroelectrics and multiferroics, leading to improved applications and commercialization of these materials. |
| URL | http://iopscience.iop.org/article/10.1088/1361-6463/aabe16/meta |
| Description | Prof. Fernando Plazaola, Department of Electricity and Electronics, UPV/EHU, Spain |
| Organisation | Materials Physics Center (CSIC-UPV/EHU) |
| Country | Spain |
| Sector | Academic/University |
| PI Contribution | Providing new samples to our partners and initiating a new research direction for their research group. |
| Collaborator Contribution | The measurements of our anti-ferroelectric materials required Sn119 Mössbauer Spectroscopy since our anti-ferroelectric compounds contain Sn Mössbauer active element rather than Fe. These measurements were not possible at NIMP Bucharest due to the radioactive source being depleted, so the tests were performed at Department of Electricity and Electronics, UPV/EHU, Spain. Under this initiative a new collaboration was developed between Dr Vopson and Prof. Fernando Plazaola. The two groups together with the ISU, NIMP and DLS co-authored an article currently submitted for publication. Under this new collaboration we now have access to Sn119 Mössbauer Spectroscopy - a very rare facility as most of the Mössbauer Spectroscopy research groups in the EU / UK operate on Fe57 instead of Sn119. The group measured our samples under this new collaborative work. |
| Impact | M.M. Vopson, X. Tan, E. Namvar, M. Belusky, S.P. Thompson, V. Kuncser, F. Plazaola, I. Unzueta, C.C. Tang, Sub-lattice polarization states in anti-ferroelectrics and their relaxation process, Current Applied Physics (2019) - article submitted and under review. |
| Start Year | 2018 |
| Description | Prof. Kuncser, NIMP Bucharest |
| Organisation | National Institute of Materials Physics Magurele-Bucharest |
| Country | Romania |
| Sector | Public |
| PI Contribution | We offered out NIMP partners access to our experimental facilities in Portsmouth, including access to thin film samples - samples already exchanged for various projects. |
| Collaborator Contribution | Dr Kuncser and his team provided the PI with detailed training on Mossbauer Spectroscopy technique for materials characterization including data analysis and fitting. The training was mostly on Fe57 transmission and surface Conversion Electron Mössbauer Spectroscopy (CEMS) and we have continuous access to these facilities. |
| Impact | Under the current project, we co-authored an article: M.M. Vopson, X. Tan, E. Namvar, M. Belusky, S.P. Thompson, V. Kuncser, F. Plazaola, I. Unzueta, C.C. Tang, Sub-lattice polarization states in anti-ferroelectrics and their relaxation process, Current Applied Physics (2019) - submitted and under review. |
| Start Year | 2017 |
| Description | Lecture at IEEE Magnetics Society, Santa Clara Chapter, San Jose and Western Digital |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Industry/Business |
| Results and Impact | In July 2018, the PI delivered two lectures at Western Digital and IEEE Magnetics Society, Santa Clara Chapter, San Jose, on the topic of applications of multiferroic materials to data storage technologies and physics and applications of anti-ferroelectric materials to non-volatile memories. The purpose of these talks, followed by open discussions and debates, was to stimulate the interest of major industrial players in Silicon Valley in the commercialization of the PI's research. |
| Year(s) Of Engagement Activity | 2018 |
| URL | https://docs.google.com/forms/d/1-RhSrS_XvI_Q01L60rCJ67shL5TMtHi9_dnLwG_l0Qs/viewform?edit_requested... |