2007 Fiscal Year Final Research Report Summary
Research on the Ground State and Transport Properties of Dipole-Type Quantum Hall States
| Project/Area Number |
18540311
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Condensed matter physics I
|
|---|
| Research Institution | The University of Tokyo |
|---|
Principal Investigator |
YOSHIOKA Daijiro The University of Tokyo, Graduate School of Arts and Sciences, Professor (30114713)
|
|---|
| Project Period (FY) |
2006 – 2007
|
| Keywords | Quantum Hall Effect / Two-dimensional electron system / Strong magnetic field / Exciton / Bose condensation / Dipole |
|---|
| Research Abstract |
It has been known that the dipole-type quantum Hall states are realized in the following two situations,(i) single layer system at Landau level filling factor 1/2, and(ii) bilayer system at total filling 1. In the present investigation We investigated these situations, and furthermore, We found that there are other situations in which the dipole-type correlation is realized. We obtained the following results.
1. We have found by DMRG (density matrix renormalization group) technique that the dipolar correlation continuously changes from intralayer correlation to interlayer correlation as the distance between the bilayer is decreased. We tries to describe these continuous transition by a mean field theory to understand the transport properties. Because of a minor problem which is not satisfactorily solved, this investigation has not been published, but We have obtained several results, and hoping to be able to publish in near future.
2. Around a positive impurity, dipolar bound states are formed. The charge distribution depends on the binding energy, and this behavior is observed by STS (scanning tunneling spectroscopy). We have calculated wave function, binding energy and local density of states for two systems, one with ordinary parabolic dispersion and the other with linear dispersion realized in graphene. We clarified the difference due to the difference in dispersion, and obtained reasonable agreement with experiment.
3. For bilayer systems with different density so that the Fermi level is at different Landau levels in the two layers, dipolar correlation developes and new kind of ground state becomes possible in wider filling factors. Until now we obtained only qualitative results. To obtain quantitaitve results, mean field analysis is underway. Once we obtained the results we proceed to DMRG calculation. The results by the mean field analysis will be published in near future.
|
