Aðferðir til að meta hraða segulhvarfa og rannsóknir á segulskyrmeindum fyrir nanóíhluti framtíðarinnar - verkefni lokið

Fréttatilkynning verkefnisstjóra

23.4.2024

Messi mynstur, t.a.m. skyrmeindir og hopfeindir, væri hægt að nota í framtíðinni til að geyma og meðhöndla gögn í tækni sem tekur minna pláss og orku en núverandi tækni. Þessar rannsóknir eru, hins vegar, á byrjunarstigi og lykilvandamálið er að finna efni þar sem þessi staðbundnu segulástönd eru nægjanlega lítil um sig en samt stöðug við herbergishita. Reikningar á slíkum kerfum hjálpa til við að fá betri skilning á eiginleikum þeirra og einnig spá fyrir um það hvaða efni gætu nýst í slíka tækni. Í verkefninu voru reikniaðferðir þróaðar fyrir slíka vinnu og þær notuðar til að rannsaka ýmis kerfi og efni til að hjálpa til við að túlka mælingar og spá fyrir um efnaeiginleika út frá grundvallarlíkingum eðlisfræðinnar og efnafræðinnar.

English:

In some materials, the atoms are like like magnets and while they typically line up in a regular way, either all pointing in the same direction (ferromagnetic) or alternate direction (antiferromagnetic), it is also possible that a more intricate magnetic structure is formed that is localised, involving a few thousand or even a few million atoms. The orientation of the magnetic moments can form various patterns and those patterns can be moved with litle energetic cost from one location to another using electrical current. These patterns, in particular skyrmions and hopfions, could possibly be used in future devices for data storage and data manipulation as a basis for  technology that is more size and energy efficient than current technology. The research is, however, at beginning stages and a key issue is to find materials where these localised magnetic structures are small enough and yet stable at room temperature. This can be aided by theoretical calculations to gain better understanding of the fundamental properties of such systems and by  predicting materials that can be useful for practical realisation of such devices. In the project, theoretical tools were developed for such work and they were applied in studies of various  systems and materials to help interpret experimental data and to predict materials properties based on basic laws of physics and chemistry.

Information on how the results will be applied:
The results will be used to aid the design of materials that can host localised magnetic states, such as skyrmions and hopfions, that may in the future become the basis of higher density data storage and manipulation.

A list of the project's outputs:
The outputs of the project are mainly the 20 scientific articles and book chapter that are listed above. In addition, the free software Spirit for calculations of magnetic properties, with user-friendly interface and powerful graphics, is a valuable output of the project.

Book chapter:
1. Exploring Potential Energy Surfaces with Saddle Point Searches, Vilhjálmur Ásgeirsson and Hannes Jónsson, in "Handbook of Materials Modeling. Volume 1, Methods: Theory and Modeling, page 689" (Springer, 2018).

Scientific Oral Presentations (not a complete list):
1. Conference titled 'Rate Theory and Long Timescale Simulations' held in Santa Fe in USA, 2018,
presenter Hannes Jónsson 
Title of presentation: 'Rate theory for magnetic transitions and application to nanoislands, elements of spin ice and skyrmions'
2. Technical University of Denmark, Physics Dpt., Magnetic Study Group, 2018, presenter Hannes
Jónsson
Title of presentation: 'Rate theory for magnetic transitions applied to nanoislands, elements of spin ice and skyrmions'.
3. European Materials Research Society Meeting (E-MRS) in Warsaw, 2018, presenter Hannes Jónsson
Title of presentation: 'Calculations of the lifetime of magnetic states in nanoislands, elements of spin ice and skyrmions'.
4. Sol-SkyMag meePng in San SebasPan, 2018, presenter prof. Valery M. Uzdin.
Title of presentation: 'Stability of Skyrmions at Various Spatial Scales'.
5. Sol-SkyMag meeting in San Sebastian, 2018, presenter Gideon Mueller, PhD student.
Title of presentation:'Skyrmion NucleaPon/Annihilation Mechanisms Revealed by Minimum Mode
Following Method'.
6. Joint European Magnetic Symposia (JEMS), Mainz, presenter Gideon Muller, PhD student.
Title of presentation: 'SPIRIT: A Spin Dynamics Simulation Software'.
7. Spin simulation workshop in York, England, 2019, presenter Aleksei Ivanov, PhD student.
Title of presentation: 'Orthogonal Spin Optimisation for Finding Energy Minima and Minimum Energy Paths of Transitions'.
8. IEEE conference on 'Advances in Magnetics 2021', presenter prof. Valery Uzdin.
Title of presentation: 'Lifetime of skyrmions in the limit of infinitesimal laZce constant'.
9. International Workshop on Computational Physics and Materials Science: Total Energy and Force MethodsTrieste conference, 2021, presenter Aleksei Ivanov, PhD student.
Title of presentation: 'Direct Optimization Methods for Excited-State Density Functional Calculations'.
10. MagnetismMeet 2022, April 2022 (on-line), presenter Hannes Jónsson
Title of presentation: 'Lifetime and transition mechanisms of skyrmions and antiskyrmions in
ferromagnets and anPferromagnets'.
11. Materials Research Society (MRS), Spring meeting, 2022, presenter Hannes Jónsson
Title of presentation: 'Lifetime of large magnetic skyrmions and antiskyrmions in discrete systems'.
12. Materials Research Society (MRS), Spring meeting, 2022, presenter Hannes Jónsson
Title of presentation: 'Annihilation of magnetic skyrmion by quantum mechanical tunneling'.
13. German Physical Society Meeting (GPD), 2023, presenter Moritz Sallerman, PhD student.
Title of presentation: 'Stability of hopfions in bulk magnets with competing exchange interaction'.

PhD theses
1. Gideon Müller, 2019, ‘Advanced methods for atomic scale spin simulations and application to
localized magnetic states'.
2. Aleksei Ivanov, 2021, 'Calculations of Ground and Excited Electronic States Using Self-Interaction
Corrected Density Functionals'.
3. Maria Potkina, 2022, ‘Stability and dynamics of chiral magnetic structures in ferro- and
antiferromagnets'.
4. Moritz Sallermann (in preparation, defence planned for January 2024). 

MS theses
1. Reynir Kristinsson, 2020, ‘The Effect of Dimensionality on Boosted Molecular Dynamics'.
2. Alec E Sigurðarson, 2023, ‘Variational Density Functional Calculations of Rydberg Excited States
with and without Self-Interaction Correction'.

BS thesis
1. Alec E. Sigurðarson, 2021, ‘Calculation of the Quantum Mechanical Effusion Rate out of a 2D Box'.
2. Þorsteinn Freygarðsson, 2022, ‘A Time Reversible Integrator for Calculations of Rates of Transitions in Magnetic Systems'.

Heiti verkefnis: Aðferðir til að meta hraða segulhvarfa og rannsóknir á segulskyrmeindum fyrir nanóíhluti framtíðarinnar/Methods for calculating the rate of magnetic transitions and research on magnetic skyrmions for future nano devices
Verkefnisstjóri: Hannes Jónsson, Háskóla Íslands
Tegund styrks: Verkefnisstyrkur
Styrktímabil: 2018-2020
Fjárhæð styrks kr. 56.006.000
Tilvísunarnúmer Rannís: 185405