2020 Fiscal Year Research-status Report
原子レベルシミュレーションによる新奇六方晶機能製材料の設計
| Project/Area Number |
19K05246
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
Das Hena 東京工業大学, 科学技術創成研究院, 特任准教授 (60836170)
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | Transition metal oxides / High-Tc magnetism / Spintronics / Materials physics / Magnetoelectricity / Quantum modelling |
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| Outline of Annual Research Achievements |
Computationally assisted investigation into high-temperature magnetic and magnetoelectric phenomena whose possible origin is attributed to unique charge ordering patterns,
1. (LuFeO3)n/(LuFe2O4)1 superlattices exhibit the exceedingly rare phenomena of high-temperature multiferroicity and magnetoelectricity. Using first-principles calculations and finite temperature simulations, we uncovered the origin of high-temperature magnetism in these superlattices and predicted a non-trivial Fe+2/Fe+3 charge ordering pattern [Nature 537, 523 (2016)]. Through our recent theoretical studies, we developed further insights into the existence of the proposed Fe+2/Fe+3 charge ordering pattern and its role to induce high-temperature magnetism via a comparative analysis of measured and simulated electronic structure and XMCD spectra [Nat. Commun. 11, 5582 (2020)].
2. In a closely related structure, i.e. in the perovskite phase of PbFeO3, we showed how a nontrivial non-polar Pb+2/Pb+4 charge ordering pattern creates an unique opportunity of inducing M=0 to M≠0 magnetic phase transition at high-temperature by effecting a redistribution of Pb ions via an external electric field and/or strain [Nat. Commun. 12, 1917 (2021)] with potential applications in spintronics.
3. Magnetic polar metals provide new opportunities for spintronics applications. In a recent study, we have predicted certain charge-ordered new magnetic polar systems consisting of 3d and 5d transition metals ions which are expected to exhibit magnetic behavior at room temperature [Chem.Mater. 33,5,1594-1606 (2021)].
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
We started systematic studies of the cation ordering and its microscopic origin in the Lu(MM')O4 systems as a function of the d-level occupancy of transition metal (TM) (M,M'), using atomistic model simulations. Due to the complexity of the structure and other factors, such as (1) presence of more than one TM ions (which are subject to strong e-e correlation), (2) numerous energetically competing magnetic phases and (3) possible charge ordering, this project needs more time than what we had initially anticipated.
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| Strategy for Future Research Activity |
Next, in the year 2021 and beyond, we aim to conduct our researches in the following directions,
1. Completion of the systematic study of the cation ordering and its microscopic origin in the Lu(MM')O4 systems as a function of the d-level occupancy of transition metal (TM) (M,M') and the development of a magnetic model. We also intend to conduct finite temperature Monte Carlo simulations to understand the magnetic properties of these systems.
2. Investigation of the magnetic properties of LuFe2O4 under the influence of electron and hole doping. In this direction we also intend to study the magnetic and polar behavior of this system under the influence of excess oxygen and oxygen deficiency.
3. Extend our study to uncover new A-site charge ordering driven unique magnetic phenomena in AMO3 (A = Pb and Bi ions, M = transition metal) perovskite systems.
4. Extend our study to computationally determine new magnetic polar metals. In this direction we intend to extend our investigations to the class of new 3d-5d transition metal based double-double and quadruple perovskite systems.
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| Causes of Carryover |
Reasons for Incurring Amount to be Used Next Fiscal Year: A portion of the Research Fund allotted for the FY 2020 will be carried forward for use in the FY 2021. The reasons why we were unable to utilize the entire fund during 2020 are given as follows, 1.The undersigned had to cancel all her business trips on account of the Corona Virus pandemic, 2.We also had to cancel our plans of inviting researchers from abroad to collaborate in our work at Tokyo Tech, (We may add here that if the pandemic situation persists in 2021, we intend to utilize the funds allocated for “Travel Support”, to develop the computational support at Tokyo Tech.)
Usage plan, Travel Support 400,000 JPY, Article Costs 100,000 JPY, Miscellaneous 107,373 JPY
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