Excitation Gap in the Normal State of Underdoped Bi
 2
 Sr
 2
 CaCu
 2
 O
 8+
 δ

Loeser, A. G.; Shen, Zhi‐Xun; Dessau, D. S.; Marshall, D. S.; Park, C. H.; Fournier, P.; Kapitulnik, A.

doi:10.1126/science.273.5273.325

Cited by 941 publications

(680 citation statements)

References 37 publications

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“…For this reason, much attention has been devoted in the past to underdoped (UD) cuprates. In addition to the SC gap, evidence for a large doping-dependent pseudogap (PG) above T c at the antinodes of UD cuprates has existed for some time 15,16 . Nevertheless, debates on the interplay between superconductivity, antiferromagnetism and PG in cuprates are ongoing.…”

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confidence: 99%

Fermi surface dichotomy of the superconducting gap and pseudogap in underdoped pnictides

Richard

Nakayama

et al. 2011

Nat Commun

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High-temperature superconductivity in iron-arsenic materials (pnictides) near an antiferromagnetic phase raises the possibility of spin-fluctuation-mediated pairing. However, the interplay between antiferromagnetic fluctuations and superconductivity remains unclear in the underdoped regime, which is closer to the antiferromagnetic phase. Here we report that the superconducting gap of underdoped pnictides scales linearly with the transition temperature, and that a distinct pseudogap coexisting with the superconducting gap develops on underdoping. This pseudogap occurs on Fermi surface sheets connected by the antiferromagnetic wavevector, where the superconducting pairing is stronger as well, suggesting that antiferromagnetic fluctuations drive both the pseudogap and superconductivity. Interestingly, we found that the pseudogap and the spectral lineshape vary with the Fermi surface quasi-nesting conditions in a fashion that shares similarities with the nodal-antinodal dichotomous behaviour observed in underdoped copper oxide superconductors.

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confidence: 99%

Fermi surface dichotomy of the superconducting gap and pseudogap in underdoped pnictides

Richard

Nakayama

et al. 2011

Nat Commun

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“…One of the most intriguing property of the underdoped high-temperature superconductors (HTSC) is the suppression of single-particle weight around the Fermi energy [1,2,3] for temperatures well above T c . As a consequence the electronic behavior of these materials deviates substantially from that of conventional superconductors.…”

Section: Instituto De Física Gleb Wataghin Universidade Estadual De mentioning

confidence: 99%

Distinguishing models for the pseudo-gap in cuprate superconductors by probing the spatial distribution of impurity states

Kübert¹

2003

Braz. J. Phys.

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We argue that the spatial distribution of resonant impurity states in underdoped high-Tc superconductors serves as a probe for distinguishing different theoretical models for the pseudogap state. Superconducting pairing fluctuations are characterized by off-diagonal short-range order which distinguishes them from other possible instabilities that could give rise to the pseudogap phenomena. Due to the mixture of particle and hole states in a superconductor an impurity resonant state is composed of both a particle and a hole-like component. On the contrary a state with a gap induced by a particle-hole instability, like a d-density wave (DDW) or spin-density wave (SDW), exhibits no off-diagonal short-range order and consequently a resonant impurity state consists of only one either particle or hole-like component. Furthermore, a charge-spin separated state shows no resonance state at all inside the gap region.One of the most intriguing property of the underdoped high-temperature superconductors (HTSC) is the suppression of single-particle weight around the Fermi energy [1, 2, 3] for temperatures well above T c . As a consequence the electronic behavior of these materials deviates substantially from that of conventional superconductors. The origin of this so-called pseudo-gap state is one of the key problems to be solved in order to understand the underlying microscopic mechanism of the phenomena of HTSC. As various different theoretical proposals for the pseudo-gap have been put forward the need of experimental probes that are able to distinguish between them is of great interest. Here we argue that scanning tunneling microscopy (STM) experiments in underdoped HTSC, that serve as a local probe of impurity states [4,5], can be used in order to differentiate between at least two classes of proposals.In one class of models the pseudo-gap is ascribed to a precursor pairing amplitude whose phase coherence is destroyed above T c [6,7]. Since such a state exhibits off-diagonal short-range order, particle and hole states get mixed and consequently an induced impurity state is composed of both a particle and a hole-like component. On the other hand in models where the origin of the pseudo-gap is due to a different type of instability (DDW, SDW, stripe order etc.) the property of particle and hole mixing is absent and thus an impurity state has only one either particle or hole-like component. This difference in the local electronic density of states (LDOS) around an impurity can be measured by scanning tunneling microscopy. This prediction can be readily used by STM experiments to detecd for the DDW state in the underdoped cuprates.The local differential conductance measured at bias voltage V by STM is proportional to the local electron density of states. Here we study the LDOS around a magnetic or non-magnetic (U = 0) impurity in a system with competing d-wave superconducting (DSC) and DDW order. The model Hamiltonian is given by (Q = (π, π))where k = 2t (cos k x ) + cos k y ) − 4t (cos k x cos k y ) − µ is the dispersion o...

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“…The pseudogap behavior [1] is observed as strong suppression of low frequency spectral weight below some characteristic temperature T * higher than transition temperature T c . This anomalous phenomenon has been observed in angle resolved photoemission spectroscopy (ARPES), [2,3] One of the most puzzling questions in pseudogap phenomena is why T * has a completely different doping dependence from T c , in spite of their possibly close relation. In this paper we demonstrate that induced local spin-singlet amplitude due to short-range spin correlations can cause a normal state pseudogap with d-wave symmetry even in the absence of pairing interactions.…”

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confidence: 99%

Short-range spin correlations and pseudogap in underdoped cuprates

Kyung

2002

Journal of Physics and Chemistry of Solids

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In this paper we show that local spin-singlet amplitude with d-wave symmetry can be induced by short-range spin correlations even in the absence of pairing interactions. In the present scenario for the pseudogap, the normal state pseudogap is caused by the induced local spin-singlet amplitude due to short-range spin correlations, which compete in the low energy sector with superconducting correlations to make Tc go to zero near half-filling.PACS numbers: 71.10. Fd, 71.27.+a The recent discovery of pseudogap in underdoped high T c cuprates has challenged condensed matter physicists for several years. The pseudogap behavior [1] is observed as strong suppression of low frequency spectral weight below some characteristic temperature T * higher than transition temperature T c . This anomalous phenomenon has been observed in angle resolved photoemission spectroscopy (ARPES), [2,3] One of the most puzzling questions in pseudogap phenomena is why T * has a completely different doping dependence from T c , in spite of their possibly close relation. In this paper we demonstrate that induced local spin-singlet amplitude due to short-range spin correlations can cause a normal state pseudogap with d-wave symmetry even in the absence of pairing interactions.First of all we argue that there are two energy scales in the problem, because the pseudogap appears as a crossover phenomenon according to experiments. The low energy (or long distance) physics of antiferromagnetic (AF) and superconducting (SC) correlations is well captured by a static mean-field approach, while the relatively high energy (or short distance) physics of the pseudogap is invisible in such a study. Thus we resort to fluctuation theory in order to describe the dynamical nature of the pseudogap, and to determine T * and pseudogap size ∆ pg . The mean-field result of the t − J model will be used below solely to find the onset of leading correlations, and to compute mean-field AF and SC order parameters for the calculation of local spin-singlet amplitude.The mean-field t − J Hamiltonian readswhere ε( k) ≃ −2tx(cos k x + cos k y ) − µ with x the hole density,m = 1/ (2N φ d ( k) = cos k x − cos k y and Q is the (commensurate) AF wave vector (π, π) in two dimensions. In this paper we restrict ourselves to a uniform solution which is just enough for our purpose. In a mean-field approximation, meanfield order already sets in when the correlation length reaches roughly one lattice spacing. This forces the above mean-field phase line ( Fig. 1(a)) to be interpreted as the onset of the corresponding short-range correlations. We identify T MF N with another crossover temperature T 0 at which some magnetic experiments such as Knight shift show their maximum. For the parameter (t/J = 3.0) used in this paper, short-range spin correlations disappear at x = x c ≃ 0.19 − 0.20 at low temperature.We introduce spin-singlet [8] correlation function1

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Excitation Gap in the Normal State of Underdoped Bi ₂ Sr ₂ CaCu ₂ O ₈₊ _δ

Cited by 941 publications

References 37 publications

Fermi surface dichotomy of the superconducting gap and pseudogap in underdoped pnictides

Fermi surface dichotomy of the superconducting gap and pseudogap in underdoped pnictides

Distinguishing models for the pseudo-gap in cuprate superconductors by probing the spatial distribution of impurity states

Short-range spin correlations and pseudogap in underdoped cuprates

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Excitation Gap in the Normal State of Underdoped Bi 2 Sr 2 CaCu 2 O 8+ δ

Cited by 941 publications

References 37 publications

Fermi surface dichotomy of the superconducting gap and pseudogap in underdoped pnictides

Fermi surface dichotomy of the superconducting gap and pseudogap in underdoped pnictides

Distinguishing models for the pseudo-gap in cuprate superconductors by probing the spatial distribution of impurity states

Short-range spin correlations and pseudogap in underdoped cuprates

Contact Info

Product

Resources

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Excitation Gap in the Normal State of Underdoped Bi ₂ Sr ₂ CaCu ₂ O ₈₊ _δ