Analysis of pinning in the linear AC response of anisotropic superconductors in oblique magnetic fields

Abstract

The linear ac response of a pinned vortex system in uniaxial anisotropic superconductors is studied. The physical model for the interpretation of electrical transport experiments in the linear regime with arbitrary angles between the applied magnetic field, the applied current, and the anisotropy axis is provided. In particular, the pinning constant (also known as Labusch parameter) and Campbell resistivity tensors are derived for arbitrary orientations. The applicability to the various tensor quantities of the well-known angular scaling laws for the angular dependence on the field orientation in uniaxial superconductors is commented. Examples of data analysis based on the present results are provided

Analysis of the Measurements of Anisotropic AC Vortex Resistivity in Tilted Magnetic Fields

“…Figure 1 illustrates the reference frame together with the magnetic induction field vector B = Bu B as an example. We briefly recall the notation and the results of [40]. In the London limit, the only source of material anisotropy is given by the phenomenological electronic mass tensor [32,34]: m ab M = diag(m ab , m ab , m c ), where m ab and m c are the inplane and out-of-plane effective mass of the charge carriers, respectively.…”

“…Hence E = ρJ, where in this case the system "transfer function" is given by the resistivity tensor ρ. The experimentally measured ρ and the material propertyρ = (σ) −1 are related by (we neglect Hall effect) [40]:…”

“…In the a.c. low frequency regime, pinning is dominant. Despite the many existing theories [5,7,35], this regime has been addressed only partially [16,33,58].In [40] a full description of the complex resistivity in the low frequency, a.c. linear regime where pinning is dominant (Campbell regime) was developed. The model incorporated the material uniaxial anisotropy and point pinning in the vortex a.c. resistivity tensor with a magnetic field applied at an arbitrary orientation.In this paper we address another important issue: we develop a model for the tensor complex resistivity in the high-frequency range (typically rf and microwaves), where both dissipation (flux-flow) and pinning give comparable contributions and must be considered at the same time.…”

“…In [40] a full description of the complex resistivity in the low frequency, a.c. linear regime where pinning is dominant (Campbell regime) was developed. The model incorporated the material uniaxial anisotropy and point pinning in the vortex a.c. resistivity tensor with a magnetic field applied at an arbitrary orientation.…”

Intrinsic anisotropy and pinning anisotropy in nanostructured YBa2Cu3O7−δ from microwave measurements

“…This feature implies that the Lorentz force changes with varying θ. The resulting electromagnetic problem has been solved earlier [43,44]. For the purpose of the analysis of the data, the essential features are as follows:…”