2023 Fiscal Year Research-status Report
結晶構造と磁気構造の同時最適化：トポロジカル磁性エレクトライドへの応用
| Project/Area Number |
22KJ1151
|
|---|
| Allocation Type | Multi-year Fund |
|---|
| Research Institution | The University of Tokyo |
|---|
Principal Investigator |
YU Tonghua 東京大学, 工学系研究科, 特別研究員(DC1)
|
|---|
| Project Period (FY) |
2023-03-08 – 2025-03-31
|
| Keywords | Electrides / Topological phases / Majorana Fermions / Half-Heuslers / Weyl semimetals |
|---|
| Outline of Annual Research Achievements |
We mainly worked on the topological electronic properties of half-Heuslers with first-principles calculations, as well as in collaboration with experiments. Half-Heuslers go under the family of electrides owing to the vacancy site per unit cell.
1. We investigated the topological boundary states at the half-Heusler interfaces. In contrast to bare surface, we uncovered that the topological interfacial states are free from dangling bonds, and show higher flexibility of tuning. We found a quantum anomalous Hall state at the GdNiSb/LuPtBi interface, which was shown to support chiral Majorana modes due to the superconductivity of LuPtBi. This work paves the avenue for topological superconductivity at the half-Heusler interfaces.
2. We studied the colossal magnetoresistance (CMR) in half-Heuslers RAuSn (R, rare earth) in collaboration with experimentalists. For the experimentally observed CMR, we calculated the electronic band structure, revealing the Lifshitz transition (emergence of Weyl points) in RAuSn as the external magnetic field is applied. On top of that, we found that the CMR could be attributed to the spin-momentum locking generated by these field-induced Weyl points, as shown by the calculated Berry curvature and spin-resolved Fermi surfaces.
|
| 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 research on the topological and magnetic properties of electrides has advanced as expected, with a primary focus on half-Heusler systems. We have identified the potential of topological half-Heuslers as platforms for chiral Majorana modes, which could be instrumental in the development of topological quantum computations. A manuscript on these findings is under preparation. In addition, we have studied the field-induced Weyl points in the half-Heusler compound HoAuSn and their role in the phenomenon of giant negative magnetoresistance. Our work on additional half-Heusler compounds in this series is ongoing, in collaboration with experimental research teams. We look forward to obtaining more significant results in the near future.
|
| Strategy for Future Research Activity |
We will investigate the superconductivity of electrides, specifically focusing on the role of interstitial electrons. Some electrides exhibit superconductivity, particularly under pressure, yet the contribution of interstitial electrons to this phenomenon remains unclear. We aim to explore this using first-principles calculations.
Additionally, we will study the colossal negative magnetoresistance in half-Heuslers RAuSn (R: rare earth), expanding our research beyond R=Ho to uncover the universal mechanisms at play. This investigation will be conducted in collaboration with experimentalists.
|
