Driven vortices in type-II superconductors: A muon spin rotation study

Abstract

We present a detailed study of vortex motion in a type-II superconductor using the muon spin rotation ͑SR͒ technique. The vortices were set in motion by an alternating transport current. By adjusting the frequency and amplitude of the driving force so that vortices "visible" to the implanted muons did not cross the sample boundaries, a SR line shape was obtained corresponding to almost perfectly ordered vortex motion. We also observed sidebands to the SR line shape which correspond to the frequency at which vortices pass the implanted muon, and allow a direct measurement of the vortex velocity. Both these features of the line shape confirm numerical predictions reported in a previous study ͓see Charalambous et al., Phys. Rev. B 66, 054506 ͑2002͔͒.

Nonequilibrium depinning transition of ac driven vortices with random pinning

“…Previous experimental and numerical studies on the nonequilibrium depinning transition have focused only on the response to the dc drive, while it is well known for the vortex system that the ac external forces, namely, the ac current I ac and the ac magnetic field, are readily used to depin and order the vortex lattice [9,13,24,25,[30][31][32][33]. For the ac current-voltage (| |-| | I V ac ac ) characteristics, an increase in the frequency f as well as the amplitude | | I ac of the ac drive I ac causes an enhancement of the amplitude | | V ac of the ac voltage.…”

Rearrangement of the Fast Driven Abrikosov Lattice in a Superconducting Amorphous Film in Tilted Field

“…This is called edge-contamination effects [14,[16][17][18]. In previous µSR measurements performed for the bulk polycrystalline Pb-In alloy the strong edge-contamination effects were actually found for dc-driven vortices [11], while in the later µSR measurements for the ac-driven vortices ordered vortex-lattice motion was observed as a result of much reduced edge effects under the ac drive [12]. Since the edge effects are negligible for thin films [19,20], the intrinsic vortex-lattice motion driven by dc force can be studied using the thin films.…”

“…In order to compare our results with most of the simulations reported so far, further experiments using only dc drive are helpful. From the standpoint, muon spin rotation (µSR) measurements [11,12], as well as neutron scattering measurements [13][14][15], are expected to provide useful information on the orientation of the fast-moving vortex lattice driven only by the dc force. The conventional µSR measurements using high-energy muons require thick (bulk) samples, while for the thick samples the formation of the ordered vortex-lattice flow is hindered by disordered vortices entering from the sample edges and hence an intrinsic behavior of the vortex-lattice motion is masked.…”

Characterization of the Biomechanical Properties of T4 Pili Expressed by Streptococcus pneumoniae—A Comparison between Helix‐like and Open Coil‐like Pili

“…Such bacteria colonize the upper respiratory tract and provoke morbidity and mortality worldwide. [22] This colonization leads most often to infections such as otitis and sinusitis. When the bacteria invade other parts of the human body, general infection induces bacterial pneumonia, other lower respiratory tract diseases, and meningitis.…”

“…When the bacteria invade other parts of the human body, general infection induces bacterial pneumonia, other lower respiratory tract diseases, and meningitis. [6,22] Despite their ubiquity, their adhesion mechanisms are not yet well understood. [23] It was only recently discovered that the S. pneumoniae bacterium, often referred to as pneumococcus, expresses pili, [1] which is confirmed by the atomic force microscopy (AFM) image presented in Figure 1 A.…”