Study on the ground state of bilayer quantum Hall systems
| Project/Area Number |
14540294
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | The University of Tokyo |
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Principal Investigator |
YOSHIOKA Daijiro The University of Tokyo, Graduate School of Arts and Science, Professor, 大学院・総合文化研究科, 教授 (30114713)
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| Co-Investigator(Kenkyū-buntansha) |
SHIBATA Naokazu The University of Tokyo, Graduate School of Arts and Science, Research Associate, 大学院・総合文化研究科, 助手 (40302385)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2002: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | two dimensional electron system / quantum Hall effect / strong magnetic field / bilayer quantum Hall system / 二層量子ホール系 / 強磁性 / 密度波状態 / ストライプ状態 / ペア状態 |
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| Research Abstract |
The object of this study is to clarify how the ground state, excitation spectrum, funneling current develop as interlayer distance, tunneling strength, spin-Zeeman splitting are changed. The methods of study are analytical method, exact diagonalization, and density matrix renormalization (DMRG) method. The development of program of DMRG for the case of bilayer systems is also one of the object of this study. For these objectives we obtained the following results.
1.Bilayer systems in which total filling is an integer with different Landau quantum numbers for each layer. : In this case the system is described by an Ising like model, when the layer index is expressed by pseudospin. It is clarified that at certain separation two types of density wave states are realized distinguished by relative phase of the density wave.
2.Bilayer system at filling one-half. In this case the ground state has various possibilities that include 331 state by Halperin, Pfaffian state, stripe state and Fermi liquid state of composite fermions, depending on the layer separation, thickness of each layer, and tunneling strength. We clarified that for certain separation and thickness corresponding to an experiment, the ground state evolves continuously as tunneling strength is varied, but the lowest excitation change discontinuously from ordinary quasiparticle state to that with non-abelian statistics. This transition explains the strange behavior observed experimentally.
3.Development of DMRG program for bilayer systems : It is not obvious to apply DMRG method to two dimensional systems. We extended our successful DMRG program for singly layer system to bilayer systems. Research of bilayer systems using this program is presently underway.
4.Behavior at large enough separation. We clarified conditions for realization of stripe states. The meaning of "charge" observed by shot noise experiments is clarified.
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Report
(4 results)
Research Products
(29 results)
