Theoretical study on vortex states in superconductors
Grant-in-Aid for Scientific Research (C)
|Allocation Type||Single-year Grants |
|Research Institution||Hokkaido University |
KITA Takafumi Hokkaido Univ., Grad.School of Science, Asso.Prof., 大学院・理学研究科, 助教授 (20186224)
|Project Period (FY)
2001 – 2004
Completed (Fiscal Year 2004)
|Budget Amount *help
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2004: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2003: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2002: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2001: ¥900,000 (Direct Cost: ¥900,000)
|Keywords||Type-II superconductors / Quantized vortices / Superfluid ^3He / Bose-Einstein condensation / Upper critical field / 超伝導 / 真木パラメータ / 電気抵抗 / エントロピー / スピン磁化率 / 超流動^3He / アルカリ原子気体 / ド・ハース-ファン・アルフェン効果 / 輸送方程式 / 超伝導準古典方程式 / 渦糸の動力学 / ゲージ不変性とホール効果 / 異方的超伝導|
Theory of the de Haas-van Alphen effect in type-II superconductors
We performed numerical and analytical studies of the de Haas-van Alphen oscillation in type-II superconductors. We derived an analytic formula for the extra attenuation observed in the vortex state, which can also be used to estimate the band and/or angle dependent gap anisotropy. Using it, we estimated gap amplitude of several materials.
Vortex structures of superfluid ^3He and spinor Base-Einstein condensates
Based on the Ginzburg-Landau equations near the transition temperature, we performed a theoretical study on the vortex-lattice structures of superfluid ^3He in rapid rotation to present an entire phase diagram. We also predicted novel vortex structures of the three-component spinor Bose-Einstein condensate.
Calculation of the Maki parameter
The Maki parameter is one of the most basic quantities in type-II superconductors which is relevant to the specific-heat jump at the transition, the change in the slope of the magn
etization curve at the transition, etc. We performed a detailed study on it to show that it has a strong dependent on the detailed Fermi-surface structures, especially in dean materials.
Calculation of the upper critical field of type-II superconductors
The upper critical field H_<c2> is one of the most basic quantities in type-II superconductors. It has been knownn for a long time that H_<c2> of clean samples depends on the detailed Fermi-surface structures. However, few detailed calculations have been performed yet. We derived an H_<c2> equation which enables us to calculate H_<c2> quantitatively by using Fermi surfaces from first-principles electronic-structure calculations. Using it, we performed detailed studies on H_<c2> of Nb, NbSe_2, and MgB_2 to find excellent quantitative agreements with experiments.
Calculation of the flux-flow resistivity of type-II superconductors near H_<c2>
The electronic resistance in the vortex state of type-II superconductors is a complicated phenomenon involving the motion of vortices which has not been understood sufficiently. We performed a detailed calculation on this flux-flow resistivity near the upper critical field to clarify the overall temperature and impurity-concentration dependences. Less
Report (5 results)
Research Products (47 results)