Stan Gheorghe, Field Stuart B, Martinis John M
Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA.
Phys Rev Lett. 2004 Mar 5;92(9):097003. doi: 10.1103/PhysRevLett.92.097003.
We have measured the maximum field for which vortices are completely expelled from a thin-film superconducting strip. Niobium strips of width W were field cooled and imaged with a scanning Hall-probe microscope. Below a critical field B(m) approximately Phi(0)/W(2) all flux was expelled; above this field vortices were observed with a density increasing approximately linearly with field. The small value of the critical field, which is orders of magnitude less than in the bulk, implies that superconducting devices should be designed with narrow wires to eliminate the generation of noise from vortex motion.
我们已经测量了能使涡旋从薄膜超导带中完全排出的最大磁场。对宽度为W的铌带进行场冷，并使用扫描霍尔探针显微镜成像。在临界场B(m)约为Phi(0)/W(2)以下时，所有磁通都被排出；高于此场时，观察到涡旋，其密度随磁场近似线性增加。临界场的值很小，比体材料中的临界场小几个数量级，这意味着超导器件应采用窄导线设计，以消除涡旋运动产生的噪声。
