Institute for Nanoscale Physics and Chemistry (INPAC), Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
1] Institute for Nanoscale Physics and Chemistry (INPAC), Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium [2] Theory of Quantum and Complex Systems (TQC), Department of Physics, Universiteit Antwerpen, Universiteitsplein 1, B-2610 Antwerpen, Belgium.
Nat Commun. 2015 Mar 16;6:6573. doi: 10.1038/ncomms7573.
One of the phenomena that make superconductors unique materials is the Meissner-Ochsenfeld effect. This effect results in a state in which an applied magnetic field is expelled from the bulk of the material because of the circulation near its surface of resistance-free currents, also known as Meissner currents. Notwithstanding the intense research on the Meissner state, local fields due to the interaction of Meissner currents with pinning centres have not received much attention. Here we report that the Meissner currents, when flowing through an area containing a pinning centre, generate in its vicinity two opposite sense current half-loops producing a bound vortex-antivortex pair, which eventually may transform into a fully developed vortex-antivortex pair ultimately separated in space. The generation of such vortex dipoles by Meissner currents is not restricted to superconductors; similar topological excitations may be present in other systems with Meissner-like phases.
超导体的独特现象之一是迈斯纳-奥赫森菲尔德效应。该效应导致在材料内部施加的磁场由于其表面附近无电阻电流（也称为迈斯纳电流）的循环而被排出。尽管对迈斯纳态进行了深入研究，但由于迈斯纳电流与钉扎中心的相互作用而产生的局部场并未受到太多关注。在这里，我们报告说，当迈斯纳电流流过包含钉扎中心的区域时，会在其附近产生两个相反方向的半环电流，从而产生束缚的涡旋-反涡旋对，最终可能会转化为完全发展的涡旋-反涡旋对，最终在空间中分离。迈斯纳电流产生这种涡旋偶极子的现象不仅限于超导体；类似的拓扑激发可能存在于具有迈斯纳类似相的其他系统中。
