Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userVortex Ordering and Dynamics on Santa Fe Artificial Ice Pinning Arrays
62
0
0.0
(
0
)
Added by
Cynthia J. Olson Reichhardt
Publication date
2021
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
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.
rate research
Read More
We examine the current driven dynamics for vortices interacting with conformal crystal pinning arrays and compare to the dynamics of vortices driven over random pinning arrays. We find that the pinning is enhanced in the conformal arrays over a wide range of fields, consistent with previous results from flux gradient-driven simulations. At fields above this range, the effectiveness of the pinning in the moving vortex state can be enhanced in the random arrays compared to the conformal arrays, leading to crossing of the velocity-force curves.
We examine pinning and dynamics of Abrikosov vortices interacting with pinning centers placed in a moire pattern for varied moire 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 moire patterns.
Conformal crystals are non-uniform structures created by a conformal transformation of regular two-dimensional lattices. We show that gradient-driven vortices interacting with a conformal pinning array exhibit substantially stronger pinning effects over a much larger range of field than found for random or periodic pinning arrangements. The pinning enhancement is partially due to matching of the critical flux gradient with the pinning gradient, but the preservation of the sixfold ordering in the conformally transformed hexagonal lattice plays a crucial role. Our results can be generalized to a wide class of gradient-driven interacting particle systems such as colloids on optical trap arrays.
We report on the realization of artificial ice using superconducting vortices in geometrically frustrated pinning arrays. This vortex ice shows two unique properties among artificial ice systems. The first comes from the possibility to switch the array geometric frustration on/off through temperature variations, which allows freezing and melting the vortex ice. The second is that the depinning and dynamics of the frozen vortex ice are insensitive to annealing, which implies that the ordered ground state is spontaneously approached. The major role of thermal fluctuations and the strong vortex-vortex interactions are at the origin of this unusual behavior.
We study the dynamics of current-biased Josephson-junction arrays with a magnetic penetration depth smaller than the lattice spacing. We compare the dynamics imaged by low-temperature scanning electron microscopy to the vortex dynamics obtained from model calculations based on the resistively-shunted junction model, in combination with Maxwells equations. We find three bias current regions with fundamentally different array dynamics. The first region is the subcritical region, i.e. below the array critical current I_c. The second, for currents I above I_c, is a vortex region, in which the response is determined by the vortex degrees of freedom. In this region, the dynamics is characterized by spatial domains where vortices and antivortices move across the array in opposite directions in adjacent rows and by transverse voltage fluctuations. In the third, for still higher currents, the dynamics is dominated by coherent-phase motion, and the current-voltage characteristics are linear.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
