2018 Fiscal Year Research-status Report
Control of carrier localization in dilute magnetic semiconductors
| Project/Area Number |
17K05494
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| Research Institution | Yokohama National University |
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Principal Investigator |
RAEBIGER HANNES 横浜国立大学, 大学院工学研究院, 准教授 (20531403)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | carrier localization / polaron states / strain engineering / magnetic semiconductors |
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| Outline of Annual Research Achievements |
We have carried out calculation of isolated defects of various polaronic defects in Ga2O3 and GaN. These include Cr, Mn, and Fe, as well as Mg acceptor type defects in GaN. The first principles calculations include both band gap correction, as well as self-interaction correction via in-house implementation. We have tested our parametrized band gap correction against a parameter-free KKR based self-interaction correction.
1. Ferromagnetic interactions of various transition metal defect pairs was investigated in Ga2O3 based systems. A new carrier-mediated magnetic interaction was discovered in Ga2O3.
2. Strain control of carrier states has been investigated for Mg acceptor defects in GaN, and various excitonic states.
3. We broadened the study to include strain effects on molecular magnetism by investigating various magnetic states of simple molecules at various interatomic distances, and discovered how strain alters core electron topologies.
The results of 1. and 2. above are presently being summarized for publication. 3 was published in Angewandte Chemie International Edition. The results on piezomagnetism in Cr and Mn doped GaN were reported at the PASPS-10 conference. A review paper on strain control of carrier states and piezomagnetism in magnetic semiconductors is being prepared.
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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
The project is processing as expected. Due to more smooth process than expected during FY2017, we also investigated strain effects on spin states of diatomic molecules. The previous year, strain control of ferromagnetism (piezomagnetism) was discovered in GaN based materials, and during FY2018, carrier-mediated ferromagnetism was also discovered in Ga2O3 based systems, and we proceed to investigate its strain control. We have calculated several adiabatic potentials for edition related states in GaN, and will carry out similar work for the Ga2O3 systems. Moreover, we were invited to summarize our discoveries on piezomagnetism in a review paper, which is under process.
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| Strategy for Future Research Activity |
We will publish 3 articles on results obtained in FY2018.
Strain effects will be investigated in detail on Ga2O3 based carrier mediated ferromagnets. Adiabatic potential energy surfaces will be calculated for various defect and defect pair systems, and complete the work on multiple magnetic interactions. A general theory of multistabilities and their strain control, together with the strain control of ferromagnetism will be developed. Results will be presented at international conferences, as well as scientific articles.
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