Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium.
Phys Rev Lett. 2011 Jul 29;107(5):057002. doi: 10.1103/PhysRevLett.107.057002.
Because of strong flux confinement in mesoscopic superconductors, a "giant" vortex may appear in the ground state of the system in an applied magnetic field. This multiquanta vortex can then split into individual vortices (and vice versa) as a function of, e.g., applied current, magnetic field, or temperature. Here we show that such transitions can be identified by calorimetry, as the formation or splitting of a giant vortex results in a clear jump in measured heat capacity versus external drive. We attribute this phenomenon to an abrupt change in the density of states of the quasiparticle excitations in the vortex core(s), and further link it to a sharp change of the magnetic susceptibility at the transition--proving that the formation of a giant vortex can also be detected by magnetometry.
由于介观超导体中强的磁通限制，在施加磁场的情况下系统的基态中可能出现一个“巨”涡旋。这种多量子涡旋可以随着施加电流、磁场或温度等因素的变化而分裂成单个涡旋（反之亦然）。在这里，我们通过量热法证明了这种转变可以被识别，因为巨涡旋的形成或分裂会导致测量热容与外部驱动力的明显跳跃。我们将这种现象归因于涡旋核心中准粒子激发态密度的突然变化，并进一步将其与转变时磁导率的急剧变化联系起来——证明了巨涡旋的形成也可以通过磁测量来检测。
