| 研究課題/領域番号 |
22K14008
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| 研究種目 |
若手研究
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| 配分区分 | 基金 |
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| 審査区分 |
小区分13030:磁性、超伝導および強相関系関連
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| 研究機関 | 沖縄科学技術大学院大学 |
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研究代表者 |
Gohlke Matthias 沖縄科学技術大学院大学, 量子理論ユニット, スタッフサイエンティスト (60860666)
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| 研究期間 (年度) |
2022-04-01 – 2024-03-31
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| 研究課題ステータス |
交付 (2022年度)
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| 配分額 *注記 |
3,120千円 (直接経費: 2,400千円、間接経費: 720千円)
2023年度: 1,170千円 (直接経費: 900千円、間接経費: 270千円)
2022年度: 1,950千円 (直接経費: 1,500千円、間接経費: 450千円)
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| キーワード | quantum spin nematic / quantum liquid crystal / quantum spin liquid / Frustrated ferromagnets / Kitaev Magnets / DMRG / tensor networks / matrix product states / frustrated ferromagnets |
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| 研究開始時の研究の概要 |
Ordering of higher-order moments, e.g. quantum spin-nematic (QSN), may occur in the absence of spin-dipolar order. In S=1/2 magnets, QSN order generically features a large degree of entanglement. Within this project I study QSN using modern numerical methods to elucidate their microscopic nature.
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| 研究実績の概要 |
With respect to my proposal, I have mostly finished goal (1) the ground state phase diagram of the square-lattice J1K model, goal (2) dynamical signatures of the quantum spin-nematic (QSN) phase, and partly goal (3) about identifying the microscopic nature of the QSN.
In particular, using matrix product state based methods, I have identified not only the QSN phase, but also a four-sublattice dipolar ordered state, a strongly canted two-sublattice antiferromagnet, and a vector-chiral phase. An additional instability was identified at incommensurate wave vectors resulting in richer dynamics of the QSN than the previously anticipated 'ghost'-Goldstone mode.
Possible numerical issues, i.e. finite-size effects, have been investigated not resulting in bigger issues.
A second model related to Kitaev-Magnets and hosting bond-quadrupole moments similar to the QSN phase of the J1K model was studied as well. The main difference being, that the latter does have much lower symmetry and quadrupole moments are naturally occurring due to off-diagonal symmetric exchange. Nonetheless, a quantum spin liquid related to a Tomanaga-Luttinger liquid in an effective 1D model has been found. A preprint is already available [arXiv:2212.11000].
I have presented results of both projects as oral presentations and as a poster presentations at conferences and as seminars. A first publication is currently in preparation.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
3: やや遅れている
理由
In my proposal, I indicated that I may have a first publication about the J1K model ready within the first year. Unfortunately, figuring out some details related to some parts of the phase diagram, and the microscopic nature of the quantum spin nematic state required more time than anticipated.
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| 今後の研究の推進方策 |
Currently, I'm preparing a first draft including results for the first three goals related to QSN in frustrated ferromagnets. Upon completion, I like to start considering extended models that are potentially more relevant/adapted to materials. I aim at starting this around the late summer.
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