We respond to P. Aos comment in arXiv:1907.09263, which suggests that vortex many-body effects are the origin of Hall sign reversal in few-unit-cell thick Bi-2212 cuprate crystals (Phys. Rev. Lett. 122, 247001 (2019)). Our experimental results are incompatible with the theoretical predictions detailed in Aos comment.
We fabricate van der Waals heterostructure devices using few unit cell thick Bi$_2$Sr$_2$CaCu$_2$O$_{8+delta}$ for magnetotransport measurements. The superconducting transition temperature and carrier density in atomically thin samples can be maintained to close to that of the bulk samples. As in the bulk sample, the sign of the Hall conductivity is found to be opposite to the normal state near the transition temperature but with a drastic enlargement of the region of Hall sign reversal in the temperature-magnetic field phase diagram as the thickness of samples decreases. Quantitative analysis of the Hall sign reversal based on the excess charge density in the vortex core and superconducting fluctuations suggests a renormalized superconducting gap in atomically thin samples at the 2-dimensional limit.
In our recent paper entitled Pairing mechanism of high-temperature superconductivity: Experimental constraints (to be published in Physica Scripta, arXiv:1012.2368), we review some crucial experiments that place strong constraints on the microscopic pairing mechanism of high-temperature superconductivity in cuprates. In particular, we show that phonons rather than spin-fluctuation play a predominant role in the microscopic pairing mechanism. We further show that the intrinsic pairing symmetry in the bulk is not d-wave, but extended s-wave (having eight line nodes) in hole-doped cuprates and nodeless s-wave in electron-doped cuprates. In contrast, the author of the Comment (to be published in Physica Scripta) argues that our conclusions are unconvincing and even misleading. In response to the criticisms in the Comment, we further show that our conclusions are well supported by experiments and his criticisms are lack of scientific ground.
We present a calculation of the Hall coefficient in 2H-TaSe2 and 2H-Cu0.2NbS2 relied on the photoemission data and compare the results to transport observations. The approach, based on the solution of the semiclassical Boltzmann equation in the isotropic tau-approximation yields high-temperature Hall coefficient consistent with the one measured directly. Taking into account the opening of the pseudogap and redistribution of the spectral weight, recently observed in angle resolved photoemission spectra of 2H-TaSe2, allows us to reproduce the temperature dependence of the Hall coefficient including prominent sign change with no adjustable parameters.
This is an extended Reply to Comment by A. Sergeev, M.Y. Reizer, and V. Mitin [arXiv:0906.2389] on our Letter [Phys. Rev. Lett. 102, 067001 (2009)]. We explicitly demonstrate that all claims by Sergeev et al. are completely unfounded, because their underlying theoretical work contains multiple errors and inconsistencies. For this reason, there is no need to revise the existing theories of thermoelectric response in superconductors.
Using the time-dependent Ginzburg-Landau equation with the complex relaxation time and the Maxwell equation, we systematically examine transverse motion of vortex dynamics in the presence of pinning disorders. Consequently, in a plastic flow phase in which moving and pinned vortices coexist, we find that the Hall voltage generally changes its sign. The origin of the sign change is ascribed to a fact that moving vortices are strongly drifted by circular current of pinned vortices and the enforced transverse moving direction becomes opposite to that by transport current. This suggests that the Hall sign change is a behavior common in all disordered type-II superconductors.
S.Y. Frank Zhao
,Nicola Poccia
,Margaret G. Panetta
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(2019)
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"Reply to P. Aos Comment on Sign reversing Hall effect in atomically thin high temperature superconductors"
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Shu Yang Frank Zhao
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