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Who am I ?
初貝 安弘 筑波大学筑波大学大学院 数理物質科学研究科 物理学専攻 教授 初貝写真
会議 & 研究会
グーグル検索:初貝
ResercherID: Y.Hatsugai
Project
メインメニュー
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- Date:
May 27, 2010- Title:
- Many-body effects on the optical and magnetic properties of doped graphene sheets
- Speaker:
- Prof. Giovanni Vignale, (University of Missouri)
- Room & time:
- D312, 15:00-16:00
- Abstract:
- I report on the results of our recent investigations of many-body effects in doped graphene sheets. First, we have calculated the first-order interaction corrections to the Drude weight, plasmon dispersion, and optical response of this system. We find that, due to the lack of Galilean invariance, both the plasmon frequency and the Drude weight are enhanced relative to the RPA value. This effect is due to the coupling between the center of mass motion and the pseudo-spin degree of freedom of the massless Dirac fermions. We then apply similar many-body theoretical methods to the calculation of the orbital magnetic susceptibility of a gas of interacting massless Dirac fermions. This susceptibility is zero in the absence of interactions, when the Fermi energy is away from the Dirac point. Our perturbative calculations show that first-order interaction corrections to the orbital magnetic susceptibility are finite and positive. Doped graphene sheets are thus unique systems in which the orbital susceptibility is completely controlled by many-body effects, leading to orbital paramagnetism.
- Web
- [poster for distribution]
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物性セミナー
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宇田川将文 氏「電荷アイスの量子融解と非フェルミ液体的挙動」 July13, 2010
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現在の時刻
今年もやります。まずは 量子力学3(遠隔).
冬は
統計力学2 改め物性理論II (大学院「ベリー接続の理論とバルクエッジ対応」).
令和二年の新年あけましておめでとうございます。今年もあと-1204日!
最新ニュース
投稿者 : hatsugai 投稿日時: 2020-11-03 10:00:50 ( 4890 ヒット) Thouless' (adiabatic) pump in one-dimension is a typical topological phenomena characterized by the Chern number that correspondes to the quantized motion of the center of mass (COM). Although the COM is only well-defined with boudary (to set the origin of the coordinate), the COM experimentally observed is given by the bulk and the edge states do not contribute. Ultimate adiabaticity, that has never been achieved experimentaly, supports the quantization of the COM supplemented by the periodicity of the system with boundaries. This is the unique bulk-edge correspondence of the pump. We here propose a generic construction using a phase boundary line of the symmetry protect phase with two parameters works as a topological obstruction of the pump in extended parameter space. The construction is purely of manybody and the interaction can be one of the parameters. Have a look at "Interaction-induced topological charge pump" by Yoshihito Kuno and Yasuhiro Hatsugai, Phys. Rev. Research 2, 042024(R), (2020) (Open access) 投稿者 : hatsugai 投稿日時: 2020-10-01 16:07:56 ( 5361 ヒット) Motivated by a historical example, the Dirac Hamiltonian as a square-root of the Klein-Gordon Hamiltonian, its lattice analogue has been discussed recently. Zero energy states are shared by the parent and its descendant. The story is more than that. Not necessarily zero energy but its high energy part can also share topological characters. We hereby propose a “square-root higher order topological insulator (square-root HOTI)” when its squared parent is HOTI. Based on the simple observation that square of the decorated honeycomb lattice is given by a decoupled sum of the Kagome and honeycomb lattices, we have demonstrate that the “corner states” of the breezing Kagome lattice with boundaries share topological characters with its descendant as the decorated honeycomb lattice. Have a look at our recent paper just published online, "Square-root higher-order topological insulator on a decorated honeycomb lattice" by Tomonari Mizoguchi, Yoshihito Kuno, and Yasuhiro Hatsugai, Phys. Rev. A 102, 033527 (2020), also arXiv:2004.03235. 投稿者 : hatsugai 投稿日時: 2020-08-16 14:53:28 ( 5569 ヒット) Adiabatic deformation of gapped systems is a conceptual basis of topological phases. It implies that topological invariants of the bulk described by the Berry connection work as topological order parameters of the phase. This is independent of the well-established symmetry breaking scenario of the phase characterization. Adiabatic heuristic argument for the fractional quantum Hall states is one of the oldest such trials that states the "FRACTIONAL" state is deformed to the “INTEGER”. Although it is intuitive and physically quite natural, there exist several difficulties. How the states with different degeneracy are deformed each other adiabatically? We have clarified the questions and demonstrated this adiabatic deformation on a torus in the paper "Adiabatic heuristic principle on a torus and generalized Streda formula" by Koji Kudo and Yasuhiro Hatsugai , Phys. Rev. B 102, 125108 (2020) (also arXiv:2004.00859) What is deformed continuously is a gap not the states ! This is also sufficient for the topological stability of the Chern number (of the degenerate multiplet) as a topological order parameter. Have a look at. 検索
バルク・エッジ対応
- [0] バルクとエッジ
- [1] 集中講義
- [2] 原論文と解説
- [3] トポロジカル秩序とベリー接続:日本物理学会誌 「解説」 [JPS-HP] [pdf]
- [4] "Band gap, dangling bond and spin : a physicist's viewpoint" [pdf] [Web]
トポロジカル相
[0]昔の科研費 - 科研費 1992年度:電子系スピン系におけるトポロジカル効果
- 科研費 1994年度:物性論におけるトポロジーと幾何学的位相
私の講演ファイルのいくつか- [1] MIT, Boston (2003)
- [2] APS/JPS March Meeting (2004)
- [3] JPS Fall meeting, JAPAN (2004)
- [4] APS/JPS March meeting (2005)
- [5] JPS Fall meeting (2005):Entanglement
- [6] Superclean workshop, Nasu (2006)
- [7] MPIPKS, Dresden (2006)
- [8] KEK, Tsukuba (2007)
- [9] ETH, Zurich (2008)
- [10] ICREA, Sant Benet (2009)
- [11] JPS Meeting, Kumamoto (2009)
- [12]HMF19, Fukuoka (2010)
- [13] NTU, Singapore (2011)
- [14] ICTP, Trieste (2011)
- [15] Villa conf., Orland (2012)
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