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Yoshida, T.; Hashimoto, M.; Ideta, S.; Fujimori, A.; Tanaka, Kiyohisa; Mannella, Norman; Hussain, Zahid; Shen, Zhi‐Xun; Kubota, Masato; Ono, Kanta; Komiya, Seiki; Ando, Yoichi; Eisaki, H.; Uchida, S.

doi:10.1103/physrevlett.103.037004

Cited by 139 publications

(142 citation statements)

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“…We extract ∆ sc (T ) from the "k-space extinction" of the QPI-inferred gap. (As in Reference [18], we do not find this k-space-extinction point to be directly related to the magnetic zone boundary, as claimed elsewhere [4].) We extract ∆ from the Bogoliubov quasi-particle dispersion, as obtained from the B-QPI inversion procedure.…”

Section: Pacs Numbersmentioning

confidence: 99%

“…The condition on γ(T c ) for the appearance of perceptible Fermi arcs in photoemission is essentially the same as the condition for the disappearance of octet peaks in the normal state. In heavily underdoped cuprates (not considered here) we cannot rule out a small contribution of B-QPI in the near vicinity but above T c presumably reflecting the fact that in ARPES the Fermi arcs are not present [18] until substantially above the nominal T c . For these more metallurgically complex cuprates near the insulating phase, more detailed experiments and theory are needed to probe the correlations between B-QPI and ARPES.…”

Section: Pacs Numbersmentioning

confidence: 99%

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Quasiparticle interference in temperature dependent-STM as a probe of superconducting coherence

Wulin

Chien

et al. 2010

Physica C: Superconductivity and its Applications

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In this paper we explore the behavior of the quasi-particle interference pattern (QPI) of scanning tunneling microscopy as a function of temperature, T . After insuring a minimal consistency with photoemission, we find that the QPI pattern is profoundly sensitive to quasi-particle coherence and that it manifests two energy gap scales. The nearly dispersionless QPI pattern above Tc is consistent with data on moderately underdoped cuprates. To illustrate the important two energy scale physics we present predictions of the QPI-inferred energy gaps as a function of T for future experiments on moderately underdoped cuprates. PACS numbers:Recently, attention in the field of high temperature superconductivity has turned to characterizing the superconducting phase in the underdoped regime. This phase necessarily differs from that of a conventional d-wave superconductor because components of the gap smoothly evolve through T c . This leads to a normal state gap or pseudogap above T c . Owing to this fact, and unlike a BCS superconductor where the order parameter and the excitation gap are identical, there are very few ways to probe directly something as fundamental as the superconducting order parameter. Within the moderately underdoped samples, which we consider throughout this paper, recent angle resolved photoemission spectroscopy (ARPES) experiments have reported [1, 2] novel signatures of superconducting order. Fermi arcs around the d-wave nodes above T c rapidly collapse [2] at the transition to form point nodes. It was argued that, within the superconducting phase, the temperature dependence of the nodal gap has finally provided [1] "a direct and unambiguous observation of a single particle gap tied to the superconducting transition". A complementary and equally valuable probe is scanning tunneling microscopy (STM) and the related quasi-particle interference (QPI) spectroscopy [3,4,5,6]. While this probe, like ARPES, is generally not phase sensitive, a controversy has arisen as to whether these techniques can, as argued experimentally [4,6], or cannot. as summarized theoretically [5,7] , distinguish coherent superconducting order from pseudogap behavior.The objective of this Letter is to provide some resolution to this controversy by studying the temperature evolution of the QPI pattern observed in STM experiments from the superconducting ground state into the pseudogap phase at T T c . We employ a microscopically derived preformed pair theory [8] that accounts [9] for all of the complex momentum and temperature dependence of the ARPES spectral gap as described above. The QPI pattern is obtained using the Fourier transform of the local density of states (LDOS) associated with a single impurity. A central result of our study is that, once compatibility with ARPES experiments is incorporated, the observation of the so-called "octet model" QPI [10,11] superconducting order: sets of consistent octet model vectors can only be found for energies less than the superconducting order parameter energy scale. B-QPI does not...

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Section: Pacs Numbersmentioning

confidence: 99%

Section: Pacs Numbersmentioning

confidence: 99%

Quasiparticle interference in temperature dependent-STM as a probe of superconducting coherence

Wulin

Chien

et al. 2010

Physica C: Superconductivity and its Applications

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“…The gap energies for both bands are very different, as in [22] and Bi2212 [7,17,18,19,20]. Red and blue shades are guide to the eye.…”

Section: Pacs Numbers: Valid Pacs Appear Herementioning

confidence: 99%

Enhanced Superconducting Gaps in the Trilayer High-TemperatureBi2Sr2Ca2Cu3O10+δ
Ideta
¹
,
Takashima
²
,
Hashimoto
³

et al. 2010
Phys. Rev. Lett.
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We have investigated the optimally doped tri-layer cuprate Bi2Sr2Ca2Cu3O 10+δ (Bi2223) by angleresolved photoemission spectroscopy, and observed energy bands and Fermi surfaces originated from the outer and inner CuO2 planes (OP and IP) separately. The OP band is overdoped (hole density ∼ 0.26/Cu) with a large d-wave gap of ∆0 ∼ 43 meV while the IP is underdoped (∼ 0.06/Cu) with an even large gap of ∆0 ∼ 60 meV. We propose that the enhancement of the ∆0 of IP is due to the minimal influence of out-of-plane disorder and that the OP gap is then enhanced through interlayer coupling, most likely a proximity effect from the IP. PACS numbers: Valid PACS appear hereIt has been well known that one of the most efficient ways to increase the critical temperature (T c ) of high-T c cuprate superconductors (HTSCs) is to increase the number of neighboring CuO 2 planes (n). T c generally increases from single-layer (n = 1), double-layer (n = 2), to tri-layer (n = 3) and then decreases for n ≥ 4 [1]. So far, several mechanisms have been proposed to explain the n dependence of T c . According to the tunneling mechanism of Cooper pairs between the CuO 2 planes, T c,max should increase with increasing n [2]. However if one takes into account the charge imbalance between the planes and the existence of competing order, T c,max takes a maximum at n = 3 [3] in agreement with experiment. Meanwhile, T c shows tendency to increase with next-nearest-neighbor Cu-Cu hopping parameter t ′ , which increases with the number of CuO 2 planes [4]. Also, T c increases with decreasing degree of out-of-plane disorder [5,6]. So far, which governs the n dependence of T c,max has been unclear because of the lack of detailed knowledge about the electronic structure of the multi-layer cuprates.In the case of Bi-based HTSCs, the optimum T c (T c,max ) increases from the single-layer Bi 2 Sr 2 CuO 6+δ (Bi2201, T c,max = 35 K), the double-layer Bi 2 Sr 2 CaCu 2 O 8+δ (Bi2212, T c,max = 95 K) to the tri-layer Bi 2 Sr 2 Ca 2 Cu 3 O 10+δ (Bi2223, T c,max = 110 K). Angle-resolved photoemission spectroscopy (ARPES) studies of double-layer Bi2212 [7,8] and four-layer Ba 2 Ca 3 Cu 4 O 8 F 2 (F0234) [10] have revealed the splitting of band dispersions and Fermi surfaces (FSs). In Bi2212, hybridization between the two CuO 2 planes causes splitting into the bonding and anti-bonding bands [7]. The ARPES study on F0234 has indicated band splitting due to the different hole concentrations of the outer CuO 2 planes and the inner CuO 2 planes, and correspondingly two FS sheets have been observed [10].The maximum superconducting (SC) gap was ∼ 60 meV, approximately twice as large as that of the smaller one. On the other hand, previous ARPES results on the tri-layer Bi2223 have not revealed band splitting and multiple FSs [11,12,13]. In the present work, we have successfully observed the band splitting of Bi2223 through a detailed photon-energy dependent study and indicated that the outer CuO 2 plane (OP) and the inner CuO 2 plane (IP) have different doping levels and gap...

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“…∆ 1 is identified as the superconducting energy gap, while a few scenarios are proposed as for the origin of ∆ 2 . PACS numbers: 74.45.+c, 74.25.Dw, The issue of two distinct energy gaps in the cuprates has been discussed by many authors, and the question whether both are related to superconductivity is still controversial [1][2][3][4]. In one scenario, one energy gap is the coherence gap which opens at T c with the onset of phase coherent superconductivity, while the other gap opens at T * which marks the cross over to the pseudogap regime and possibly the creation of uncorrelated pairs [5].…”

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confidence: 99%

Observation of Two Andreev-Like Energy Scales inLa2−xSrxCuO4Superconductor–Normal-Metal–Superconductor Junctions

Koren

Kirzhner

2011

Phys. Rev. Lett.

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Conductance spectra measurements of highly transparent ramp-type junctions made of superconducting La 2−x Sr x CuO 4 electrodes and non superconducting La 1.65 Sr 0.35 CuO 4 barrier are reported. At low temperatures below T c , these junctions have two prominent Andreev-like conductance peaks with clear steps at energies ∆ 1 and ∆ 2 with ∆ 2 > 2∆ 1 . No such peaks appear above T c . The doping dependence at 2 K shows that both ∆ 1 and ∆ 2 scale roughly as T c . ∆ 1 is identified as the superconducting energy gap, while a few scenarios are proposed as for the origin of ∆ 2 . PACS numbers: 74.45.+c, 74.25.Dw, The issue of two distinct energy gaps in the cuprates has been discussed by many authors, and the question whether both are related to superconductivity is still controversial [1][2][3][4]. In one scenario, one energy gap is the coherence gap which opens at T c with the onset of phase coherent superconductivity, while the other gap opens at T * which marks the cross over to the pseudogap regime and possibly the creation of uncorrelated pairs [5]. In contrast to this scenario, some ARPES measurements show only a single energy gap, which indicate that the superconducting gap and the pseudogap might be the same entity [6,7]. In another scenario, the regime above T c in the underdoped cuprates which exhibits a signature of the condensate, can be attributed to strong superconducting fluctuations. This behavior was found in measurements of the Nernst effect [8], whose T c (onset) values scale with doping roughly as the superconducting dome. This effect therefore, is related to T c and apparently depends on more than one energy scale of the condensate. Previous point contact measurements of tunneling and Andreev conductance have shown that the tunneling gap which scales as T * is larger than the Andreev gap which follows T c [2,[9][10][11]. In the present study we report on similar conductance measurements in ramp-type junctions of the La 2−x Sr x CuO 4 (LSCOx or LSCO) system, but due to their high transparency we observe mostly Andreev gaps. Surprisingly, we find two different such gaps in this system below T c both of which scale versus doping roughly as the superconducting dome. Only single gaps were observed in previous conductance measurements in . The results though show that in Refs. [10][11][12] the gaps follow T c while in Ref.[13] the gaps scale as T * . The present low energy Andreev peak in the conductance spectra is attributed to the superconducting gap, while a few scenarios are discussed in relation to the origin of the second high energy feature in the spectra. Fig. 1. This spectrum has three pronounced features. The first is a narrow zero bias conductance peak (ZBCP), the second is a dome like peak of intermediate width which is superimposed on a third feature which is even broader. The conductance data is therefore the result of a sum of three components which can be written as The inset shows the derivative of the conductance data of the main panel.A typical conductance spectrum of a LS...

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Universal versus Material-Dependent Two-Gap Behaviors of the High-TcCuprate Superconductors: Angle-Resolved Photoemission Study ofLa2−xSrx

Cited by 139 publications

References 34 publications

Quasiparticle interference in temperature dependent-STM as a probe of superconducting coherence

Quasiparticle interference in temperature dependent-STM as a probe of superconducting coherence

Enhanced Superconducting Gaps in the Trilayer High-TemperatureBi2Sr2Ca2Cu3O10+δ
Ideta
¹
,
Takashima
²
,
Hashimoto
³

et al. 2010
Phys. Rev. Lett.
Self Cite
72
9
50
0
View full text Add to dashboard Cite

Observation of Two Andreev-Like Energy Scales inLa2−xSrxCuO4Superconductor–Normal-Metal–Superconductor Junctions

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Universal versus Material-Dependent Two-Gap Behaviors of the High-TcCuprate Superconductors: Angle-Resolved Photoemission Study ofLa2−xSrx

Cited by 139 publications

References 34 publications

Quasiparticle interference in temperature dependent-STM as a probe of superconducting coherence

Quasiparticle interference in temperature dependent-STM as a probe of superconducting coherence

Enhanced Superconducting Gaps in the Trilayer High-TemperatureBi2Sr2Ca2Cu3O10+δIdeta1, Takashima2, Hashimoto3 et al. 2010Phys. Rev. Lett.Self Cite729500View full textAdd to dashboardCite

Observation of Two Andreev-Like Energy Scales inLa2−xSrxCuO4Superconductor–Normal-Metal–Superconductor Junctions

Contact Info

Product

Resources

About

Enhanced Superconducting Gaps in the Trilayer High-TemperatureBi2Sr2Ca2Cu3O10+δ
Ideta
¹
,
Takashima
²
,
Hashimoto
³

et al. 2010
Phys. Rev. Lett.
Self Cite
72
9
50
0
View full text Add to dashboard Cite