Motion of Flux Lines and Structure of Electric Field in Superconductor under Longitudinal Magnetic Field

纵向磁场下超导体中磁通线的运动和电场结构

• 批准号: 06650025
• 负责人: MATSUSHITA Teruo
• 金额: $ 1.28万
• 依托单位: Kyusyu Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06650025/
• 关键词: superconductivity; longitudinal magnetic field; motion of flux line; structure of electric field; Josephson's equation

The structure of electric field on a surface of superconducting slab Pb-In specimens which carry a transport current under a parallel magnetic field is investigated. It turns out that the negative electric field opposed to the direction of applied current appears at a certain portion under a sufficiently high magnetic field and a certain pattern of the electric field is observed. However, the periodicity of the structure is not ascertained because of a shorter length of specimens than the structure determined from the ratio between the DC field and the self field of the current. It is found that the transverse electric field also appears in the resistive state and takes positive and negative values in correlation with the longitudinal electric field. Thus, it is concluded that the transverse electric field does not originate from the Hall effect but comes from the motion of flux lines as well as in the cylindrical superconducting specimen. As a result, the Josephson equation does not hold correct but it is theoretically shown that the electric field is described as E=B*v-gradphi, where B is the magnetic flux density and v is the velocity of flux lines. Here phi is not a simple electrostatic potential but is a potential which leads to the induced electric field due to the flux motion. While E*v gives rise to the negative electric field, the energy dissipation is associated only with-grad phi.The differential resistivity on the whole specimen increases monotonically with increasing magnetic field and agrees qualitatively with the Bardeen-Stephen model under the transverse magnetic field.

本文研究了平行磁场作用下载流Pb-In超导平板样品表面的电场结构。结果表明，在足够高的磁场下，与施加电流的方向相反的负电场出现在特定部分，并且观察到电场的特定图案。然而，结构的周期性是不确定的，因为一个较短的长度比从直流场和电流的自场之间的比率确定的结构的试样。发现在电阻态下也存在横向电场，并且横向电场与纵向电场有正、负相关关系。由此得出结论，横向电场不是源于霍尔效应，而是来自磁通线的运动以及圆柱形超导样品中的横向电场。因此，约瑟夫森方程不成立，但理论上表明电场被描述为E=B*v-gradphi，其中B是磁通量密度，v是磁通线的速度。这里，φ不是简单的静电势，而是由于磁通运动而导致感应电场的势。当E*v引起负电场时，能量耗散仅与-grad φ有关，整个样品的微分电阻率随磁场的增加而单调增加，定性地符合横向磁场下的Bardeen-Stephen模型。