Hall anomaly by vacancies vs fragments of vortex lattice: Quantitative analyses of new evidences

Abstract

Despite numerous recent studies on the Hall anomaly following the discovery of cuprate superconductivity, the origin of this phenomenon remains contentious. We demonstrate that a previously proposed mechanism, in which vacancy-on-fragment of the flux-line crystal, provides an alternative explanation for the observations of $\rm{Bi_{2}Sr_{2}CaCu_{2}O_{x}}$ thin films made by Nitzav and Kanigel [Phys. Rev. B. 107, 094516 (2023)], without the need for adjustable parameters. Specifically, we show that the power-law behavior of $ρ_{xy}$ over $ρ_{xx}$, with and without sign reversal, is consistent with the picture of vacancies versus fragments. Interestingly, we find that the effective length of vortex lines is consistently 1.5 unit cells (UC) across different experiments, independent of film thickness.