2001 Fiscal Year Final Research Report Summary
Theoretical Study of Superfluid ^3He Thin Films
| Project/Area Number |
10203208
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas (B)
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| Allocation Type | Single-year Grants |
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| Research Institution | Kyoto University |
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Principal Investigator |
OHMI Tetsuo Graduate School of Science, KYOTO UNIVERSITY, Professor, 大学院・理学研究科, 教授 (70025435)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAHARA Mikio Kinki University, Professor, 理工学部, 教授 (90189019)
IKEDA Ryusuke Graduate School of Science, KYOTO UNIVERSITY, Associate Professor, 大学院・理学研究科, 助教授 (60221751)
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| Project Period (FY) |
1998 – 2000
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| Keywords | superfluid ^3He thin film / spinor BEC / vortex glass phase |
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| Research Abstract |
T. Ohmi and M. Nakahara investigated superfiuid ^3He films and spinor BEC and R. Ikeda studied the vortex glass phase of high temperature superconductors. We have got the following results.
1) Superfluid ^3He films : We have studies the transition temperatures T_c and the symmetry of the Cooper pairs of thin films with specularly reflecting walls. We have found that the ABM state is the most stable at T_c, the transition temperature oscillates as a function of film thickness and it has a tendency to increase as the film thickness decreases.
2) Spinor BEC : Alkali atoms have the spin. The spin is fixed by the magnetic field in magnetically trapped BEC but it becomes free in optically trapped BEC. We investigated the features of this spinor BEC. Since the order parameters of superfluid have the multi-components, the phase separation occurs, depending on the situation. We analyzed the spin domain and structure of the domain wall. We also show that there exist multiple superfluid phases in the spinor BEC. The spin points the direction of the magnetic field so we can control the spin texture with use of the external magnetic field. We proposed the method to create a vortex by changing the magnetic field.
3) Spin glass phase : Since the system is nearly two-dimensional and the fluctuation is very strong in the high temperature superconductor, the T-H phase diagram is completely different from that of conventional superconductors. When we consider the phase diagram in the system with strong fluctuations, we can not neglect the contribution of the point and line defects to the supercoducting state in the presence of magnetic field. By carefully examining effects of the point and line defects, we show the so-called spin glass phase exists in the T-H phase diagram and make clear the features of the vortex glass phase.
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