Origin of the anomalous Hall effect in the overdopedn-type superconductorPr2−xCex

Abstract

The anomalous magneto-transport properties in electron doped (n-type) cuprates were investigated using Hall measurements at THz frequencies. The complex Hall angle was measured in overdoped Pr2−xCexCuO4 samples (x=0.17 and 0.18) as a continuous function of temperature above Tc at excitation energies 5.24 and 10.5 meV. The results, extrapolated to low temperatures, show that inelastic scattering introduces electron-like contributions to the Hall response. First principle calculations of the Hall angle that include current vertex corrections (CVC) induced by electron interactions mediated by magnetic fluctuations in the Hall conductivity reproduce the temperature, frequency, and doping dependence of the experimental data. These results show that CVC effects are the source of the anomalous Hall transport properties in overdoped n-type cuprates. PACS numbers: 74.72.Jt 78.20.Ls 71.18.+y 71.10.Ay 71.45.GmThe anomalous properties of the cuprates above the superconducting transition temperature have presented many puzzling challenges to the paradigms of condensed matter physics. In particular the unusual magnetotransport has often been cited as evidence that the cuprates are not Fermi liquids [1,2]. Despite the large simple convex hole-like Fermi surfaces observed by angular resolved photoemission (ARPES), both optimally doped n-and ptype cuprates exhibit anomalous and strongly temperature dependent Hall coefficients. In overdoped n-type cuprates, R H has zero crossings that suggest a mixed electron and hole response. Consensus on an explanation for the apparent non-Fermi liquid behavior of the cuprates has not been achieved despite much theoretical and experimental effort [1, 2].One proposed explanation involves current vertex corrections (CVC) to the standard relaxation time approximation (RTA) for the Hall conductivity [2]. In this Fermiliquid scenario, inelastic electron interactions mediated by antiferromagnetic (AF) fluctuations are the operative mechanism. In an alternative explanation thermally induced magnetic fluctuations at finite temperatures reconstruct the FS dynamically leading to fluctuating electron and hole-like Fermi surface segments over an area determined by the AF correlation length and a time scale associated with the AF correlation time [3]. In both of these scenarios, Fermi liquid behavior is recovered at T=0 where inelastic scattering and thermal fluctuations vanish.In this letter we directly address these issues by extending magnetotransport measurements into the frequency domain in the electron doped cuprates. We report temperature and doping dependent Hall data on overdoped Pr 2−x Ce x CuO 4 (PCCO) at THz frequencies 10 meV. At finite frequencies near zero temperatures where inelastic scattering is still operative but magnetic fluctuations are weak, we observe a strong suppression of the Hall response which corresponds to electronlike contributions coming into σ xy , even at T=0. Our experimental observations together with direct comparisons between our magnetotransport data and first-princip...

Terahertz Hall measurements on optimally doped single-crystalBi2Sr2CaCu2O8+x

“…In overdoped Pr 2−x Ce x CuO 4 ͑PCCO͒ in the T → 0 limit, the measured dc-R H agrees with the value calculated from ARPES data within the RTA, and both are consistent with Luttinger's theorem. 26 In underdoped n-type cuprates, the number density of the electron pocket derived from ARPES measurements is consistent with the stoichiometric doping as measured in Sm 1.86 Ce 0.14 CuO 4 ͑Ref. 29͒ and Nd 2−x Ce x CuO 4Ϯ␦ .…”

“…This technique, together with quantitative comparisons with ARPES and other transport data, have proven very successful in affirming the causal mechanism of the extremely anomalous behavior of the Hall effect in n-type cuprates in the overdoped regime 26,27 as well as the underdoped regime in the paramagnetic state. 28 Furthermore, the technique has proven a reliable and sensitive probe of FS reconstruction as established in underdoped n-type cuprates below the Néel temperature, 29,30 manifesting as a drastically reduced Hall mass.…”

“…The theory successfully accounted for the doping, temperature, and frequency dependence of the IR Hall data on overdoped electron-doped cuprates. 26,28 Calculated results of the IR Hall response are shown in Fig. 2.…”

“…This discrepancy can be accounted for by including current vertex corrections ͑CVCs͒ produced by electron-magnon scattering in a Fermi-liquid-based theoretical analysis, a mechanism which is notably supported in n-type cuprates. [26][27][28] …”

Optical and Hall conductivities of a thermally disordered two-dimensional spin-density wave: Two-particle response in the pseudogap regime of electron-doped high-Tcsuperconductors

“…Our theory is in a sense complementary to that of Kontani et al who used a fluctuation-exchange approximation most applicable in the overdoped region. 56,57 The theory has two important parameters: λ which controls the gap amplitude, and ε 0 which represents the effect of non-zero temperature. The methods we employ would also be applicable to the hole-doped cuprates, but in these materials the spin fluctuations are peaked at an "incommensurate" (i.e.…”