Hall-effect anomaly nearTcand renormalized superconducting fluctuations inYBa2

Abstract

Measurements of the Hall effect and the resistivity on precisely-patterned YBa2Cu3O7−x thin films in magnetic fields B from 0.5 to 6 T oriented parallel to the sample crystallographic c axis reveal a sign reversal of the Hall coefficient for B ≤ 3 T. The data are compared to the full, quantitative expressions based on the renormalized fluctuation model for the Hall conductivity. The model offers a satisfactory understanding of the experimental results, for moderate fields and temperatures near the critical region, provided that the inhomogeneity of the critical temperature distribution is also taken into account. We also propose an approach how vortex pinning that strongly affects the magnitude of the Hall coefficient can be incorporated in the model.

Mixed-state Hall effect and flux pinning in Ba(Fe1−xCox)Wang1, Sou2, Yang3 et al. 2011Phys. Rev. B

“…In early works, transport measurements on certain high-T c superconductors have shown an anomalous sign reversal of Hall resistivity, [13][14][15][16][17][18] which has been attributed to vortex pinning and vortex-vortex interaction, [19][20][21] or strong thermal fluctuation calculated in the time-dependent Ginzburg-Landau model. 22 Related theoretical works can be also found out in the references listed in Refs.…”

Non-ohmic Electrical Transport Properties Above the Critical Temperature in Optimally and Underdoped Superconducting YBa2Cu3O6+x

“…A strong non-ohmic effect can be noticed in the region of ρ yx < 0, where the negative minimum is dramatically enhanced at higher electric fields. Such behavior has been observed and discussed previously [10,14,16,34] and has been attributed to the fact that pinning forces are overcome in elevated currents.…”

Transverse vortex commensurability effect and sign change of the Hall voltage in superconducting YBa2Cu3O7−δ thin films with a nanoscale periodic pinning landscape

“…The sign of σ N xy is the same as that of the normal-state Hall effect, i.e., positive in YBCO, but the sign of σ S xy depends on details of the Fermi surface [9,15,16,[60][61][62]. The Hall effect's sign reversal and behavior in a wide range of magnetic fields in unpatterned HTSCs can be quantitatively modeled [12].…”

“…In a temperature down sweep, a sign reversal of the Hall coefficient R H below the critical temperature T c appears with precursor effects already visible above T c in the superconducting fluctuation range [10]. Several theoretical models have attempted to explain this puzzling observation and, based on a renormalized Ginzburg-Landau model for superconducting order parameter fluctuations [11], the experimental observations could be satisfyingly modeled [12]. In these theories, subtleties of the Fermi surface determine the sign of the vortex Hall effect [13][14][15][16].In a different approach, vortex pinning as the origin of the reversed polarity of the vortex Hall effect has been discussed [17][18][19][20][21].…”