arXiv subjects

B. Jankó

Publications and source records attributed to B. Jankó.

3 recordsLinked to original sources

arXiv2021

Vortex Ordering and Dynamics on Santa Fe Artificial Ice Pinning Arrays

We numerically examine the ordering, pinning and flow of superconducting vortices interacting with a Santa Fe artificial ice pinning array. We find that as a function of magnetic field and pinning density, a wide variety of vortex states occur, including ice rule obeying states and labyrinthine patterns. In contrast to square pinning arrays, we find no sharp peaks in the critical current due to the inherent frustration effect imposed by the Santa Fe ice geometry; however, there are some smoothed peaks when the number of vortices matches the number of pinning sites. For some fillings, the Santa Fe array exhibits stronger pinning than the square array due to the suppression of one-dimensional flow channels when the vortex motion in the Santa Fe lattice occurs through the formation of both longitudinal and transverse flow channels.

cond-mat.supr-con↗

arXiv2020

Vortex Dynamics, Pinning, and Magic Angles on Moiré Patterns

We examine pinning and dynamics of Abrikosov vortices interacting with pinning centers placed in a moiré pattern for varied moiré lattice angles. We find a series of magic angles at which the critical current shows a pronounced dip corresponding to lattices in which the vortices can flow along quasi-one-dimensional channels. At these magic angles, the vortices move with a finite Hall angle. Additionally, for some lattice angles there are peaks in the critical current produced when the substrate has a quasiperiodic character that strongly reduces the vortex channeling. Our results should be general to a broad class of particle-like assemblies moving on moiré patterns.

cond-mat.supr-con↗

arXiv2011

Formation of multi-quanta vortices in superconductors: electronic, calorimetric and magnetic evidence

The ground state with vorticity larger than one in mesoscopic superconductors in applied magnetic field may manifest as a `giant'-vortex, where all vortices coalesce into a single singularity of the order parameter. Such a multi-quanta vortex may 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 heat-capacity measurements, as the formation or splitting of a giant-vortex results in a clear jump in measured heat capacity vs. 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 formation of a giant-vortex can also be detected by conventional magnetometry.

cond-mat.supr-con↗