Universal nodal Fermi velocity

Zhou, Xueguang; Yoshida, T.; Lanzara, Alessandra; Bogdanov, P. V.; Kellar, S. A.; Shen, Kyle; Yang, Wanli; Ronning, F.; Sasagawa, T.; Kakeshita, T.; Noda, T.; Eisaki, H.; Uchida, S.; Lin, C. T.; Zhou, Fang; Xiong, Jianyin; Ti, W. X.; Zhao, Zhongxian; Fujimori, A.; Hussain, Zahid; Shen, Z.‐X.

doi:10.1038/423398a

Cited by 339 publications

(420 citation statements)

References 12 publications

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“…1a, a characteristic dispersion kink appears in the pristine sample at approximately 50-80 meV in the nodal cut where the d-wave superconducting gap vanishes. This is in good agreement with the results of previous reports 1,[7][8][9] . A similar kink is also observed in both Zn-substituted and Ni-substituted Bi2212 (Fig.…”

Section: Espite Years Of Intensive Research On Copper Oxidesupporting

confidence: 83%

Impurity effects on electron–mode coupling in high-temperature superconductors

et al. 2005

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D espite years of intensive research on copper oxidesuperconductors with high transition temperatures (T c ), the driving force of superconductivity has not yet been clarified. Angle-resolved photoemission spectroscopy (ARPES) 1-3 measurements have uncovered an important contribution of lattice vibrations (phonons) to superconductivity, sparking a fierce debate on the nature of the 'glue'-phonons or magnetic excitations-binding together the superconducting Cooper pairs 1-11 . However, it is difficult to distinguish these two pairing forces owing to their similar energy scales. Here, we propose a fresh approach to investigate the origin of many-body interactions in these superconductors: an impurity-substitution effect on the low-energy dynamics, which is a magnetic analogue of the isotope effect used for classical superconductors. Our ARPES results reveal that the impurity-induced changes in the electron self-energy show a good correspondence to those of magnetic excitations 12-18 , indicating the importance of spin fluctuations to electron pairing in the high-T c superconductors.The interaction of electrons with bosonic excitations (phonons or spin excitations), which causes the pairing of electrons and leads to superconductivity, produces a small anomaly in the energy dispersion in the vicinity of the Fermi level (E F ); ref. 19. High-resolution ARPES has directly observed a small band anomaly, now known as a 'kink' , in high-T c cuprates. In order to clarify the origin of the kink and its relationship with the high-T c superconductivity, the momentum, carrier concentration, temperature and CuO 2 -layer-number dependences of the kink have been investigated intensively 1-3,5-11 . However, no consensus on the origin of the kink has yet been reached. The largest discrepancy is the assignment of the kink in the antinodal region around the (π, 0) point in the Brillouin zone, where the dispersion kink is observed to be the strongest and the d-wave gap becomes maximum in the superconducting state. Three possible candidates, the magnetic mode 12-15 , the B 1g phonon 20,21 and the longitudinal optical phonon 22 , have been proposed. However, as all of these modes have similar energies of 40-70 meV, there are no convincing experimental clues to distinguish these apparently different possibilities. One effective approach to find the origin of the kink is to investigate the impurity effect using impurity atoms with different spin states but with similar atomic masses, because it is expected that even a small amount of such impurities will significantly affect the magnetic environment in the CuO 2 plane while not producing a marked change in the lattice vibration. This approach is regarded as an 'isotope' effect for magnetically mediated superconductors, analogous to the conventional isotope effect for phonon-mediated superconductors. Here, we report ultrahigh-resolution ARPES results on Zn-substituted and Ni-substituted samples of the Bi-based high-T c cuprate superconductor Bi 2 Sr 2 CaCu 2 O 8+δ (Bi2212) to find the ori...

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Section: Espite Years Of Intensive Research On Copper Oxidesupporting

confidence: 83%

Impurity effects on electron–mode coupling in high-temperature superconductors

et al. 2005

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“…These have been interpreted as a signature of the coupling of quasiparticles to collective excitations (bosons). In LSCO x 0:22 a kink is observed [29] at about 70 meV which corresponds approximately to the onset of the higher-energy excitations that we have observed. Recent ARPES experiments [30 -33] indicate further quasiparticle anomalies at higher energies which persist into the overdoped region [30].…”

mentioning

confidence: 60%

“…ARPES experiments [27][28][29] have observed ''kink'' structures in the quasiparticle dispersion of a number of systems including LSCO. These have been interpreted as a signature of the coupling of quasiparticles to collective excitations (bosons).…”

mentioning

confidence: 99%

Persistence of High-Frequency Spin Fluctuations in Overdoped SuperconductingLa2−xSrxCuO4(x=
Lipscombe
¹
,
Hayden
²
,
Vignolle
³

et al. 2007
Phys. Rev. Lett.
98
22
106
1
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We report a detailed inelastic neutron scattering study of the collective magnetic excitations of overdoped superconducting La 1:78 Sr 0:22 CuO 4 for the energy range 0 -160 meV. Our measurements show that overdoping suppresses the strong response present for optimally doped La 2ÿx Sr x CuO 4 which is peaked near 50 meV. The remaining response is peaked at incommensurate wave vectors for all energies investigated. We observe a strong high-frequency magnetic response for E * 80 meV suggesting that significant antiferromagnetic exchange couplings persist well into the overdoped part of the cuprate phase diagram. DOI: 10.1103/PhysRevLett.99.067002 PACS numbers: 74.72.Dn, 74.25.Ha, 75.40.Gb, 78.70.Nx The occurrence of high-temperature superconductivity is widely believed to be connected to the cuprates' spin degrees of freedom [1]. Thus, we might expect strong spin fluctuations to coexist with superconductivity over the whole superconducting phase diagram. The spin excitations have been well characterized for the insulating antiferromagnetic (AF) [2] and lightly doped [3-6] compositions. For optimally doped compositions, structured excitations have been observed over a wide energy range [7,8]. However, little is known about the high-energy spin dynamics on the overdoped side of the cuprate phase diagram. One of the best materials to investigate this region is single layer La 2ÿx Sr x CuO 4 (LSCO). This system can be doped sufficiently to destroy the superconductive behavior [9], allowing the spin excitations to be studied across the entire superconducting dome. Studying the overdoped part of the phase diagram offers a different view on the emergence of the superconducting state. In contrast to the underdoped regime, superconductivity does not emerge from the ''pseudogap'' state [10]. Rather, it emerges from what appears to be a strongly correlated metallic state [11].In this Letter, we report an inelastic neutron scattering (INS) study of the magnetic response 00 q; ! of an overdoped superconducting sample over a wide energy range (0 -160 meV) and throughout the Brillouin zone. We have chosen the composition La 1:78 Sr 0:22 CuO 4 (T c 26 K), which shows a substantial drop in T c with respect to optimal doping but is nevertheless superconducting (see Fig. 1). We find that the spin excitations are dramatically modified from those observed at optimal doping: The strong peak in the local susceptibility 00 ! present [8] in La 1:84 Sr 0:16 CuO 4 near 50 meV is suppressed, and the remaining response is incommensurate and strongest around E 10 meV and E * 80 meV. Thus, strong spin excitations persist well into the overdoped region of the cuprate phase diagram as required by magnetically mediated models of superconductivity.La 1:78 Sr 0:22 CuO 4 has a tetragonal structure and we use tetragonal indexing to label reciprocal space Q ha ? kb ? lc ? . The magnetic excitations in LSCO are 2D as the strongest magnetic couplings are within the CuO 2 planes. Thus, usually we quote in-plane components of Q. In this notation, the p...

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“…Here ∆ is the maximal gap of d-wave superconductivity at T = 0. Also recently the universality of the Fermi velocity v = 2.3 × 10 7 cm/sec has been established by the angle resolved photoemission spectrum [6].…”

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confidence: 99%

Gossamer superconductivity, new paradigm?

Won¹,

Haas

Maki

et al. 2005

Physica Status Solidi (b)

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Key words cuprate, d-wave superconductivity, d-wave density wave PACS 74.70.-b We shall review our recent works on d-wave density wave (dDW) and gossamer superconductivity (i.e. dwave superconductivity in the presence of dDW) in high-Tc cuprates and CeCoIn5. a) We show that both the giant Nernst effect and the angle dependent magnetoresistance (ADMR) in the pseudogap phases of the cuprates and CeCoIn5 are manifestations of dDW. b) The phase diagram of high-Tc cuprates is understood in terms of mean field theory, which includes two order parameters ∆1 and ∆2, where one order paremeter is from dDW and the other from d-wave superconductivity. c) In the optimally to the overdoped region we find the spatially periodic dDW, an analogue of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, becomes more stable. d) In the underdoped region where ∆2/∆1 ≪ 1 the Uemera relation is obtained within the present model. We speculate that the gossamer superconductivity is at the heart of high-Tc cuprate superconductors, the heavy-fermion superconductor CeCoIn5 and the organic superconductors κ-(ET)2Cu(NCS)2 and (TMTSF)2PF6.

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Universal nodal Fermi velocity

Cited by 339 publications

References 12 publications

Impurity effects on electron–mode coupling in high-temperature superconductors

Impurity effects on electron–mode coupling in high-temperature superconductors

Persistence of High-Frequency Spin Fluctuations in Overdoped SuperconductingLa2−xSrxCuO4(x=
Lipscombe
¹
,
Hayden
²
,
Vignolle
³

et al. 2007
Phys. Rev. Lett.
98
22
106
1
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Gossamer superconductivity, new paradigm?

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Universal nodal Fermi velocity

Cited by 339 publications

References 12 publications

Impurity effects on electron–mode coupling in high-temperature superconductors

Impurity effects on electron–mode coupling in high-temperature superconductors

Persistence of High-Frequency Spin Fluctuations in Overdoped SuperconductingLa2−xSrxCuO4(x=Lipscombe1, Hayden2, Vignolle3 et al. 2007Phys. Rev. Lett.98221061View full textAdd to dashboardCite

Gossamer superconductivity, new paradigm?

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Persistence of High-Frequency Spin Fluctuations in Overdoped SuperconductingLa2−xSrxCuO4(x=
Lipscombe
¹
,
Hayden
²
,
Vignolle
³

et al. 2007
Phys. Rev. Lett.
98
22
106
1
View full text Add to dashboard Cite