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Wang, Zhaozhong; Chien, T. R.; Ong, N. P.; Tarascon, J. M.; Wang, E.

doi:10.1103/physrevb.43.3020

Cited by 152 publications

(86 citation statements)

References 18 publications

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“…1 However, R H and thermoelectric power gradually increase and eventually change sign to positive with further doping Ce. 2,3,4,5,6,7 Similar feature has been observed with changing the oxygen content. 4,8 In another ntype cuprate P r 2−x Ce x CuO 4+δ (PCCO), the change of R H sign with temperature 9,10,11 and doping 12 were also observed.…”

supporting

confidence: 77%

“…Especially for x=0.025, such low temperature insulating behavior becomes obvious around 240 K, similar to the report by Onose et al 1 However, the metallic behavior can be observed in the high temperature range. For the overdoped samples, metallic behavior exists in the whole temperature range and superconductivity was observed and slightly overdoped superconducting (x∼0.17) compositions, the change of Hall coefficient sign with temperature has been reported 4,6,8,10 . The conventional single-carrier transport can not explain such behavior adequately, and two types of the carriers have to be used to explain these behaviors.…”

mentioning

confidence: 95%

“…It is believed that for the electron-doped cuprates two different types of bands take effect in the transport behavior of those samples as emphasized by many groups 3,4,6 . Here, let us look at it from a different point of view.…”

mentioning

confidence: 99%

“…Therefore, one can conclude that the single band model is not valid in these cases. In the frame of two-bands model 3,4,6 , eR H x/V is proportion to npµ 2 p −neµ 2 e (npµp+neµe) 2 ( n p , n e are the carrier density of different bands. µ p , µ e are the mobility of each band, respectively).…”

mentioning

confidence: 99%

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Influence of doping level on the Hall coefficient and on the thermoelectric power inNd2−xCexCuO4+δ

Wang

et al. 2005

Phys. Rev. B

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Hall coefficient RH and thermoelectric power TEP are studied systematically in the single crystals N d2−xCexCuO4 (NCCO) with different x from underdoped to overdoped regime. RH and TEP decrease and change their sign from negative to positive with increasing doping level x. A striking feature is that the temperature dependence of the Hall angle follows a T 4 behavior in the underdoped regime, while a T 2 law in the overdoped regime. This behavior is closely related to the evolution of Fermi surface with doping level observed by the angle-resolved photoemission spectroscopy (ARPES).PACS numbers: 74.72. Jt, 74.25.Fy, 74.25.Jb N d 2−x Ce x CuO 4+δ (NCCO) belongs to a quite interesting class of materials which is called as electron doped cuprates. With the substitution of Nd by Ce, the electrons were injected to the CuO 2 plane since the Hall coefficient (R H ) and the thermoelectric power (TEP) remains negative. 1 However, R H and thermoelectric power gradually increase and eventually change sign to positive with further doping Ce. 2,3,4,5,6,7 Similar feature has been observed with changing the oxygen content. 4,8 In another ntype cuprate P r 2−x Ce x CuO 4+δ (PCCO), the change of R H sign with temperature 9,10,11 and doping 12 were also observed. Those strange behaviors strongly indicate that at moderate doping, NCCO and PCCO have two bands with different types of charge carriers, one is hole carrier and the other is electron carrier. The Fermi surface (FS) obtained by ARPES indirectly supports this conclusion. Armitage et al. 13 suggested that the existence of FS patch in the slightly doped samples is marked by an electron pocket at (π, 0) and the FS patch gradually changes to a large hole-like FS with the appearance of section near the zone diagonal (π/2, π/2) of the Brillouin zone with increasing doping. The presence of the two separate FS pockets may result from the band folding effect induced by the antiferromagnetic correlations. 14 The theoretical calculations indicate that the two FS pockets can be effectively described as a two-band system. 14,15 Recently, Luo and Xiang proposed a weakly coupled two-band model with d x 2 −y 2 pairing symmetry to account for the anomalous temperature dependence of superfluid density (ρ s ) in n-type cuprate superconductor very well. 16 Hall angle is another interesting feature. It is well known that Hall angle follows a T 2 law in hole doped system. Anderson 17 emphasized that the transport is governed by two different scattering time for the high T c cuprates, τ tr (T −1 ) for in-plane resistivity and τ H (T −2 ) for Hall angle. Another point of view is that the cotangent of Hall angle (cotθ H ) is proportional to the square of the scattering rate which can be independently measured by the zero-field resistivity. 18 Recently, a striking finding by Ando et al. 19 is that the temperature dependence of resistivity nearly follows T 2 in lightly doped YBCO and LSCO. Their finding gives another picture that in lightly hole-doped cuprates the transport behavior is Fermi-liqui...

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supporting

confidence: 77%

mentioning

confidence: 95%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Influence of doping level on the Hall coefficient and on the thermoelectric power inNd2−xCexCuO4+δ

Wang

et al. 2005

Phys. Rev. B

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“…In this cuprate, the qp contribution to the Nernst signal is large. From early Hall-effect experiments [81,82] as well as ARPES, it is known that both electron-like and hole-like bands contribute to the qp current. The presence of both bands leads to a change in sign of the normal-state Hall coefficient R H in OP crystals [81,82].…”

Section: Electron-doped Cupratementioning

confidence: 99%

Nernst effect in high-Tcsuperconductors

2006

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The observation of a large Nernst signal eN in an extended region above the critical temperature Tc in hole-doped cuprates provides evidence that vortex excitations survive above Tc. The results support the scenario that superfluidity vanishes because long-range phase coherence is destroyed by thermally-created vortices (in zero field), and that the pair condensate extends high into the pseudogap state in the underdoped (UD) regime. We present a series of measurements to high fields H which provide strong evidence for this phase-disordering scenario. Measurements of eN in fields H up to 45 T reveal that the vortex Nernst signal has a characteristic "tilted-hill" profile, which is qualitatively distinct from that of quasi-particles. The hill profile, which is observed above and below Tc, underscores the continuity between the vortex-liquid state below Tc and the Nernst region above Tc. The upper critical field (depairing field) Hc2 determined by the hill profile (in slightly UD to overdoped samples) displays an anomalously weak T dependence, which is consistent with the phase-disordering scenario. We contrast the Nernst results and Hc2 behavior in hole-doped and electron-doped cuprates. Contour plots of eN (T, H) in the T -H plane clearly bring out the continuous extension of the low-T vortex liquid state into the the high-T Nernst region in holedoped cuprates (but not in the electron-doped cuprate). The existence of an enhanced diamagnetic magnetization M that survives to intense H above Tc is obtained from torque magnetometry. The observed M scales accurately like eN above Tc, confirming that the large Nernst signal is associated with local diamagnetic supercurrents that persist above Tc. We emphasize implications of the new features in the phase diagram implied by the high-field results, and discuss several theories.

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HTSC cuprate phase diagram using a modified Boson–Fermion–Gossamer model describing competing orders, a quantum critical point and possible resonance complex

Squire

March

Booth

2009

Int J of Quantum Chemistry

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There has been considerable effort expended toward understanding high temperature superconductors (HTSC), and more specifically the cuprate phase diagram as a function of doping level. Yet, the only agreement seems to be that HTSC is an example of a strongly correlated material where Coulomb repulsion plays a major role. This manuscript proposes a model based on a Feshbach resonance pairing mechanism and competing orders. An initial BCS-type superconductivity at high doping is suppressed in the two particle channel by a localized preformed pair (PP) (Nozieres and Schmitt-Rink, J Low Temp Phys, 1985, 59, 980) (circular density wave) creating a quantum critical point. As doping continues to diminish, the PP then participates in a Feshbach resonance complex that creates a new electron (hole) pair that delocalizes and constitutes HTSC and the characteristic dome (Squire and March, Int J Quantum Chem, 2007, 107, 3013;, 108, 2819. The resonant nature of the new pair contributes to its short coherence length. The model we propose also suggests an explanation (and necessity) for an experimentally observed correlated lattice that could restrict energy dissipation to enable the resonant Cooper pair to move over several correlation lengths, or essentially free. The PP density wave is responsible for the pseudogap as it appears as a "localized superconductor" since its density of states and quasiparticle spectrum are similar to those of a superconductor (Peierls-Frö hlich

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Positive Hall coefficient observed in single-crystalNd2−xCe

Abstract: The Hall coefficient RH

Cited by 152 publications

References 18 publications

Influence of doping level on the Hall coefficient and on the thermoelectric power inNd2−xCexCuO4+δ

Influence of doping level on the Hall coefficient and on the thermoelectric power inNd2−xCexCuO4+δ

Nernst effect in high-Tcsuperconductors

HTSC cuprate phase diagram using a modified Boson–Fermion–Gossamer model describing competing orders, a quantum critical point and possible resonance complex

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