Mechanics of individual isolated vortices in a cuprate superconductor

Abstract

. Although vortex matter has been studied extensively 1,6,7 , the static and dynamic properties of an individual vortex have not. Here, we use magnetic force microscopy (MFM) to image and manipulate individual vortices in a detwinned YBa 2 Cu 3 O 6.991 single crystal, directly measuring the interaction of a moving vortex with the local disorder potential. We find an unexpected and marked enhancement of the response of a vortex to pulling when we wiggle it transversely. In addition, we find enhanced vortex pinning anisotropy that suggests clustering of oxygen vacancies in our sample and demonstrates the power of MFM to probe vortex structure and microscopic defects that cause pinning.

Nanomechanics of an individual vortex in an anisotropic type-II superconductor

“…3b in Ref. 1. Moreover, a semiquantitative agreement of these data can be obtained if one takes λ of the order of several tenths of a micron and ε lxy ∼ 10 pN.…”

“…In particular, the authors of Ref. 1 found a dramatic enhancement of the response of a vortex to pulling when they wiggled it transversely. In addition, they discovered enhanced vortex pinning anisotropy in this crystal.…”

Imaging the Statics and Dynamics of Superconducting Vortices and Antivortices Induced by Magnetic Microdisks

“…It is also crucial to take into consideration the interaction of quantized flux lines with ferromagnets in order to understand more practical systems such as magnetic force microscopy measurements of superconducting samples [9,10], the enhancement of the superconducting critical current in superconductorferromagnet hybrid systems [11][12][13][14], or why superconducting levitating trains do not derail in sharp curves [15,16].…”

Measurement of the magnetic penetration depth of a superconducting MgB2thin film with a large intraband diffusivity

“…However, the irregular shape of individual vortices suggests the presence of inhomogeneity in the superfluid density on a sub-micron scale, which may be related to impurities. The maximum force gradient [max(∂f /∂z)] at the center of the vortex qualitatively indicates that the magnitude of λ at 15 K is larger than that at 4 K. [29][30][31] In order to determine the absolute value of λ, we performed Meissner experiments. The force between the tip magnetic moment (a distance d above the sample) and the shielding currents induced by the tip field is equal to the force between the real tip and the image tip, with the mirror plane at a distance λ below the sample's surface.…”