Anisotropic vortex channeling inYBa2Cu3O7–δthin films with

Abstract

Scanning Hall probe microscopy has been used to make a microscopic study of flux structures and dynamics in yttrium barium copper oxide thin-film disks containing a regular 10-m-period square array of 2.5-m-sized holes ͑antidots͒. Images obtained after field cooling the sample to 77 K in very low fields reveal that the holes can trap two flux quanta at this temperature. Scans obtained after zero-field cooling ͑ZFC͒ to 77 K and a subsequent applied field cycle clearly display preferential flux channeling along chains of antidots in the direction of maximum induction gradient. Remarkably, upon reversal of field sweep direction, we observe flux "streaming" out of the holes towards the sample edges with almost uniform density flux "stripes" bridging the holes in the exit direction. We estimate that the antidots can preferentially trap about 15 flux quanta in these ZFC experiments. Classical electrodynamics simulations of our samples appear to be in good qualitative agreement with our results, indicating that many of the observed phenomena may be geometrical effects that depend primarily on the shape and topology of the sample, and potential applications are discussed.

Mechanism for flux guidance by micrometric antidot arrays in superconducting films

“…Similarly, a periodic arrangement of antidots can cause effective flux drainage of a sample in the descending branch of a magnetic field ramp. 25 It was also found that when the antidot lattice breaks the symmetry of the overall sample shape, or when the antidots have nontrivial shapes, the critical current density can become anisotropic 3,26 and the flux motion can be enhanced in unexpected directions. 27 Whereas superconducting films containing complex arrangements of antidots can today be readily produced using, for example, optical lithography, the theoretical modeling of the local and global features of the flux dynamics in such systems is challenging.…”

Bulk high-Tcsuperconductors with drilled holes: how to arrange the holes to maximize the trapped magnetic flux?

“…It has been measured in [21] that increasing the hole diameter by a factor of 2 results in a magnetization drop of ∼ 80%. In the particular limit of YBCO thin films of rectangular shape with microscopic holes, the Bean critical state has also been simulated in [22]. However, to our knowledge, none of these previous works has studied the influence of the hole pattern on the magnetization drop.…”

Microwave Absorption by Vortices in Superconductors with a Washboard Pinning Potential

“…In this work the influence of isotropic pointlike disorder on the guiding of vortices was discussed for the first time. Later on, lithographic techniques have been routinely employed to create periodic pinning arrays consisting of practically identical nanostructures in the form of, e.g, microholes [20,21], magnetic dots [22], and stripes [23]. The main idea all these works share is to suppress periodically the superconducting order parameter.…”

“…With regard to a theoretical description it has to be stated that a full and exact account of the nonlinear vortex dynamics in superconducting devices proposed in these works [20][21][22][23] in a wide range of external parameters is not available due to the complexity of the periodic PP used in these references. Due to this reason it has been proposed by the authors in a number of articles to study a simpler case, such as a WPP periodic in one direction [12,[24][25][26][27] or bianisotropic [28].…”