Periodic Reporting for period 2 - TSAR (Topological Solitons in Antiferroics)
Reporting period: 2022-05-01 to 2023-10-31
The TSAR project aims at using topology for information technology purposes.
We intend here to concentrate on topological phenomena in real space, and in particular topologically protected ‘objects’ (for instance magnetic skyrmions), with an energy barrier associated with a change in their topology class.
These solitonic objects have been found mainly in magnetic materials like ferromagnets and there are recent reports that ferroelectrics may also be able to host them. However, antiferroic orders like antiferromagnetism or antiferroelectricity would provide extra properties e.g. a faster control or an increased robustness.
Thus, TSAR aims at designing antiferroic materials for the nucleation and control of topological solitons using various stimuli envisioned with a particular emphasis on ultra-fast vortex light pulses carrying angular orbital momentum.
The project is mainly fundamental because it pertains to very recent advances in materials and optics. But it also targets to lead proofs-of-concept for agile, low-power, room-temperature spintronic and electronic devices based on antiferroic topological materials, which could participate in societal challenge of reduction of tomorrow’s information and communication technologies.
We intend here to concentrate on topological phenomena in real space, and in particular topologically protected ‘objects’ (for instance magnetic skyrmions), with an energy barrier associated with a change in their topology class.
These solitonic objects have been found mainly in magnetic materials like ferromagnets and there are recent reports that ferroelectrics may also be able to host them. However, antiferroic orders like antiferromagnetism or antiferroelectricity would provide extra properties e.g. a faster control or an increased robustness.
Thus, TSAR aims at designing antiferroic materials for the nucleation and control of topological solitons using various stimuli envisioned with a particular emphasis on ultra-fast vortex light pulses carrying angular orbital momentum.
The project is mainly fundamental because it pertains to very recent advances in materials and optics. But it also targets to lead proofs-of-concept for agile, low-power, room-temperature spintronic and electronic devices based on antiferroic topological materials, which could participate in societal challenge of reduction of tomorrow’s information and communication technologies.
TSAR is focused on mastering topological objects in two main classes of materials i.e. antiferromagnets - AF - and (anti)ferroelectrics- (A)FE. In this first 30 months, experimental and theoretical work have produced results on all fronts. Firstly, a substantial effort on materials has allowed to produce antiferroic films with high reliability. Among the available materials, some show great promise for AF skyrmion generation. In particular, beside the totally optimized synthetic antiferromagnets, strain engineered BiFeO3 can now lead to compounds where the intrinsic cycloidal state is suppressed putting the material at the verge of metastability of individual entities: AF skyrmions. On the electric side, beside the perfectly mastered PbTiO3-based superlattices, huge progress has been made in the growth and understanding of antiferroelectric PbZrO3. Its complex antiferroelectric phase is now well studied and topologically protected ferri-electric entities have been observed. Electric-field and temperature behaviour of the AFE/FE transition have also been clarified by our extensive tools, some of them developed for the TSAR project. On that front, our consortium avails of the state of the art capabilities to image topological entities including NV center magnetometry along with its noise mapping, MFM and PFM microscopies and atomically resolved TEM with operando capabilities. Dynamical measurements at the sub-picosecond timescale have also been designed using optics and will be applied in the second part of the project. Moreover, on the theoretical front, several codes have been developed either on atomistic magnetic/electric calculations, along with phase-field and DFT and a second-principles model has been constructed. Some interesting progress has also been made in the theory for soliton nucleation with OAM light using already built effective Hamiltonian models in Molecular Dynamics simulations using Laguerre-Gauss beams.
Regarding the challenge of writing topological AF entities, light pulses carrying OAM have been optimized and used on Synthetic Antiferromagnets (SAF), and BiFeO3. Skyrmions can now be written with OAM light in SAFs, but the role of AOM is not yet understood.
Regarding the challenge of writing topological AF entities, light pulses carrying OAM have been optimized and used on Synthetic Antiferromagnets (SAF), and BiFeO3. Skyrmions can now be written with OAM light in SAFs, but the role of AOM is not yet understood.
By the end of this project, TSAR will have opened uncharted routes in topological concepts of antiferroic materials: anti-ferromagnets and anti-ferroelectrics. It is expected to have a substantial impact, at the fundamental level, of several active fields of condensed matter physics such as spintronics and oxides electronics as well as boosting research on anti-ferroelectrics.
TSAR will also add novelty in the field of light/matter interactions as light angular orbital momentum will be used to write and move the entities. This should allow for an ultra-fast generation of inhomogeneous ferroic textures including more complex solitons with higher topological charges.
On the technological front, the impact of TSAR lies in the medium term, when the power consumption inherent to current-driven metal spintronic architectures will reach unsustainable levels.
The technology we will invent in this project will bring solutions to overcome these issues by providing potentially smaller, faster and lower power alternatives. Our advances will empower ICT companies and foster the development of a European based industry using topological solitons in insulators. Besides, energy saving and reducing the associated carbon emissions is perhaps the biggest societal challenge for the coming decades. The natural properties of topological objects such as AFM and AFE skyrmions in insulators should allow for their exploitation as the ultimate energy-efficient bit elements for future electronics. Therefore, technologies based on TSAR will make a crucial contribution to the drastic reduction of the energy used for computation and storage.
TSAR will also add novelty in the field of light/matter interactions as light angular orbital momentum will be used to write and move the entities. This should allow for an ultra-fast generation of inhomogeneous ferroic textures including more complex solitons with higher topological charges.
On the technological front, the impact of TSAR lies in the medium term, when the power consumption inherent to current-driven metal spintronic architectures will reach unsustainable levels.
The technology we will invent in this project will bring solutions to overcome these issues by providing potentially smaller, faster and lower power alternatives. Our advances will empower ICT companies and foster the development of a European based industry using topological solitons in insulators. Besides, energy saving and reducing the associated carbon emissions is perhaps the biggest societal challenge for the coming decades. The natural properties of topological objects such as AFM and AFE skyrmions in insulators should allow for their exploitation as the ultimate energy-efficient bit elements for future electronics. Therefore, technologies based on TSAR will make a crucial contribution to the drastic reduction of the energy used for computation and storage.