2021 Fiscal Year Research-status Report
Diagnosing topological phononic materials by first-principle calculations
| Project/Area Number |
21K13865
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
Zhang Tiantian 東京工業大学, 理学院, 特任助教 (50875101)
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| Project Period (FY) |
2021-04-01 – 2023-03-31
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| Keywords | topological band theory / topological materials / DFT / chiral phonons / Dirac points |
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| Outline of Annual Research Achievements |
I have been carrying out research on topological band theory, and propose a simpler way for diagnosing topological band crossings in the spinless electronic band structure and phonon/photon band structure [1]. I and my collaborators also establish the conservation rules for chiral phonons in the 3D non-symmorphic systems [2], which is also verified by experiments [3]. We also discover new topological materials with exotic topological bulk properties associated with topological surface states [4-6].
[1] Journal of Physics D: Applied Physics 54 (41), 4002; [2] Phys. Rev. Research 4 (1), L012024; [3] arXiv:2110.11604
[4] npj Computational Materials 7, 195; [5] Phys. Rev. Research 3 (4), L042037; [6] arXiv:2201.03238
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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
Topological states in phononic systems are topological band crossings, which cannot be diagnosed easily before. To fix such problem, we propose a new topological band theory which only need to calculate the irreducible representations at most 8 high-symmetry momenta. Since topological band theory in phononic systems can be also applied to spinless electronic systems and other bosonic systems, our new theory will draw wide attention and make huge influence.
Since chirality is also one of the topological properties for phonons, my collaborators and I establish the conservation rules for chiral phonons involved physical process in the 3D non-symmorphic systems, which is also verified by experiments.
Further new topological states are also discovered in magnetic systems and spinful systems.
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| Strategy for Future Research Activity |
Now I am still working on discovering new topological band theory in phononic systems, which will still be the main topic in the next year.
I am also studying the chiral phonon involved many-body processes, such as electron-phonon coupling and exciton-phonon coupling process in both 2D and 3D materials. Hope we can discover the unique feature of topological phonons in these processes.
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