2017 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 harried out electronic structure calculations of GaN and Ga2O3 with a variety of impurities. As magnetic impurities, we consider Mn and Fe in GaN, and Cr and Mn in Ga2O3. For GaN, we also consider Mg impurities as electrically active "spectator" defects. Band gap corrections via NLEP, transition element 3d corrections via +U, and self-interaction corrections via lambda -parameters have been successfully implemented. The various correction parameters are tested and cross-validated against available experimental data.
For the magnetic Mn and Fe impurities in GaN, we have discovered a variety of carrier states, ranging from trapped small polaron to extended states. These calculations have been carried out in unstrained as well as axially strained samples, leading to the discovery of control of carrier localization by strain engineering. We published these results in Physical Review Materials[1], and presently are conducting similar calculations also for Mg impurities.
Similar calculations are being prepared for Ga2O3, and other oxide systems. For magnetic impurities in Ga2O3, we are presently preparing a publication of calculated results, which will be submitted for publication within shortly.
Publications: [1] H. Raebiger et al, Phys. Rev. Materials vol 2,p. 024402, Jan 2018.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
Our calculations of GaN systems have proceeded more quickly than expected, and we have already demonstrated strain control of carrier localization in magnetic semiconductors and published the results. We have also succeeded in optimizing the various computational parameters for several materials, and are in the process of calculating magnetic interactions in unstrained systems and under strain. For several systems, we have already calculated adiabatic potentials, which were scheduled for the second year of the project. Due to rapid progress, we are considering also to include a wider range of oxide materials in the study.
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| Strategy for Future Research Activity |
We proceed as planned, by calculating both pairwise magnetic interactions, and adiabatic potential energy surfaces for magnetic impurities in our candidate systems. Mg acceptors are included as spectator defects. Within FY2018, we will first publish our results of magnetic impurity calculations in Ga2O3. This will be followed by calculation of magnetic interactions as a function of impurity separation. Large supercells will be prepared including also spectator impurities, and a large part of these calculations is expected to finish already during this fiscal year.
This will allow us to follow up, as planned, to the final stage of the project in FY2019 to calculate multiple magnetic interactions with the influence of multiple spectators, including strain effects, and collect sufficient data to summarize a general theory of multistabilities of magnetic impurities in semiconductors and insulators.
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Research Products
(4 results)
