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

Abstract

The transverse (Hall) voltage in thin films of the high-temperature superconductor YBa2Cu3O 7−δ with an artificial periodic pinning array is investigated. Columnar defect regions along the crystallographic c axis, in which superconductivity is suppressed, are created by irradiation with He + ions through a silicon stencil mask. The commensurate arrangement of magnetic flux quanta with the artificial defect lattice is confirmed by maxima of the critical current and minima of the resistance, respectively. The magnetic field dependence of the transverse voltage reveals a commensurability effect characterized by a narrow peak of the Hall coefficient with reversed polarity compared to the background signal. This signature of vortex matching disappears at larger vortex velocities substantiating its close connection with enhanced pinning of vortices at the periodic pinning landscape.evident by the fact that the two above-mentioned theories do not fully agree on the vortex Hall effect and, even more, in a real system the vortex dynamics are influenced by additional forces [3] with the Magnus force as one of the prominent examples [4][5][6]. But not only is the equation of motion of a single vortex a source of still ongoing discussion, the importance of vortex many-body effects has been pointed out, too [7].The discovery [8] that the vortex Hall effect can exhibit an opposite polarity than the hole like normal-state Hall effect in underdoped and optimally doped [9] copperoxide high-T c superconductors (HTSCs) is in striking contrast to the traditional models for vortex dynamics [1][2][3][4]. 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]. Also, the dimensionality of the pinning arXiv:1809.01914v2 [cond-mat.supr-con]

Fast Dynamics of Guided Magnetic Flux Quanta

“…In the decorated Nb films, magnetic flux quanta more easily move along the Co stripes than overcome the barriers of the washboard pinning poten- tial induced by the nano-array [29,40]. For this reason we present the measured voltages without Hall-like contributions [41,42] arising in our samples due to the pinning anisotropy [43,44] and discriminate the longitudinal V + and transverse V + ⊥ voltage components which are even with respect to magnetic field reversal, namely…”

Vortex Dynamics, Pinning, and Magic Angles on Moiré Patterns

“…The vortex flow is generally more ordered for θ < 12 • even at incommensurate angles since the vortices follow large scale zig-zag patters, such as is shown for θ = 6.6 • in the SI [34]. Experimentally it is possible to measure transverse vortex motion with various techniques [36,37]. Although we find strong variations in the critical current as a function of the angle θ, we do not observe pronounced features as a function of field.…”

Nano-patterning of cuprate superconductors by masked He+ ion irradiation: 3-dimensional profiles of the local critical temperature

“…Details on the observation of fluxon commensurability effects in the critical current of YBCO films, patterned with artificial defects by MIBS, are reported elsewhere [12]. In addition, an unconventional critical state [22] and a sign change of the Hall effect [28] have been observed in such samples.…”