Empirically anisotropic behavior of the transport property of superconductivity can be investigated on a thin film single crystal such as YBa2Cu3 O7-d a-oriented film. By lithography along various directions of the single crystal film, anisotropy of transport current density in (110) (113), and a-axis-oriented YBCO thin film at various Temperature and magnetic field has been studied. Detail explaination and experimental results are given in RG (see publication, J.Z. Wu and W.K. Chu, Philosophical Magazine B67, 587 (1993), and Physical Rev. B49,1381 (1994).
The microscopic superconductor theory (Eliashberg-Nambu formalism) is naturally anisotropic unless averaged over the Fermi surface. The reason lies in phonon anisotropy that in turn leads to anisotropy of the Eliashberg function, so that the superconducting order parameter, Δ, has to be isotropic even when the Fermi surface is perfectly spherical.
Dr. Anil K. Yadav, some gaps are anisotropic, i.e., they have k dependence in the function Δ = Δk, even in the case of BCS theory, this can be detected using ultrasound measurements αs-i(T)below Tc along with different crystal directions, for example, i: [1,0,0] or [1,1,0].
Take a look at the example of Aluminum:
Article Anisotropy of Superconducting Energy Gap in Aluminium Determ...
Best Regards.
- Badges
- Science topic
- Similar topics
- Engineering
- Control Theory