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.

研究了在平行磁场作用下携带输运电流的超导铅锌板试样表面的电场结构。结果表明，在足够高的磁场下，与施加电流方向相反的负电场在一定的部分出现，并观察到一定的电场模式。然而，由于样品的长度比由直流场与电流自场之比确定的结构短，因此无法确定结构的周期性。发现横向电场也出现在电阻态，且与纵向电场呈正负相关。由此可以得出结论，横向电场并非来自霍尔效应，而是来自磁通线的运动以及圆柱形超导试样。因此，Josephson方程不正确，但从理论上表明，电场的描述为E=B*v-gradphi，其中B为磁通量密度，v为通量线的速度。这里不是一个简单的静电势，而是一个由于磁通运动导致感应电场的势。当E*v产生负电场时，能量耗散只与-梯度有关。整个试样的电阻率随磁场的增大而单调增大，在横向磁场作用下与Bardeen-Stephen模型定性一致。