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Pei, Shiyou; Jorgensen, J. D.; Dąbrowski, B.; Hinks, D.G.; Richards, D.R.; Mitchell, A.W.; Newsam, J. M.; Sinha, Sunil K.; Vaknin, David; Jacobson, Allan J.

doi:10.1103/physrevb.41.4126

Cited by 400 publications

(175 citation statements)

References 39 publications

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confidence: 93%

“…The results are understood as due to very small charge transfer between the unequal Bi sites [5]. The crystal structure also evolves with doping and at room temperature, for x = 0.0 -0.1 it is monoclinic, from x = 0.1 to 0.3 it is orthorhombic and above x = 0.3 up to 0.5( = the solubility limit), it is cubic [11].In this work we study the electronic structure of Ba 1−x K x BiO 3 with x = 0.2, 0.33 and 0.46. For x = 0.2, the system is semiconducting ; for x = 0.33 we are across the critical concentration x c ∼ 0.3 and into the metallic phase with a T c of 31 K; x= 0.46 is overdoped with a T c of ∼24 K. We have done a detailed study with the purpose of investigating the role of charge order (in the absence of magnetic order) on the electronic structure and superconducting transition in Ba 0.67 K 0.33 BiO 3 .…”

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Electron-phonon coupling induced pseudogap and the superconducting transition inBa0.67K0.33BiO
Chainani
¹
,
Yokoya
²
,
Shin
³

et al. 2001
Phys. Rev. B
30
3
19
0
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We study the single particle density of states (DOS) across the superconducting transition (Tc = 31 K) in single-crystal Ba0.67K0.33BiO3 using ultrahigh resolution angle-integrated photoemission spectroscopy. The superconducting gap opens with a pile-up in the DOS, ∆(5.3 K) = 5.2 meV and 2∆(0)/kB Tc = 3.9. In addition, we observe a pseudogap below and above Tc, occurring as a suppression in intensity over an energy scale up to the breathing mode phonon(∼ 70 meV). The results indicate electron-phonon coupling induces a pseudogap in Ba0. 67K0.33BiO3 . PACS numbers: 74.25.Jb, 74.25.Kc, 79.60.Bm From a variety of experiments and theory, it is clear that the high temperature cuprate superconductors belong to a special class of materials. Some of the important aspects of the cuprates are quasi twodimensionality, short-range antiferromagnetic correlations, an anisotropic pseudogap in the normal phase, and d x 2 −y 2 symmetry of the superconducting gap [1,2]. In contrast, the perovskite series Ba 1−x K x BiO 3 (BKBO) is three-dimensional, contains no transition metal ions, has no magnetic order but still exhibits the highest T c known for an oxide other than the cuprates [3]. The superconductivity in the BKBO series was preceded by the analogous BaBi 1−x Pb x O 3 (BPBO) series which shares the same parent BaBiO 3 (BBO) [4]. The role of electron-phonon coupling in the properties of the BKBO and BPBO series originates in the charge density wave (CDW) state of BBO.The parent BBO is expected to be a metal from band theory with a half-filled Bi 6s band, but the near perfect nesting possible in BBO causes a three-dimensional CDW gap to open up in the DOS [4,5]. The CDW in BBO is coupled to the breathing mode phonon which is due to the contraction and expansion of oxygen octahedra surrounding neighbouring Bi ions. Subtitution with K in the Ba-site results in a semiconductor-metal transition at a critical x c ∼ 0.3. While the CDW state is weakened by substitution, resulting in a systematic lowering of the CDW energy upon doping, the breathing mode phonon is observed even in the metallic phase [6]. Optical conductivity studies [7] suggest remnant local CDW order in the superconducting compositions with x = 0.33 and 0.4. EXAFS measurements[8] also show that there are two types of Bi ions, with short-and long-bond nearest neighbour Bi-O distances. On increasing x, the short and long Bi-O distances become equivalent around x = 0.4. This picture is derived from the formally Bi 3+ and Bi 5+ ions constituting the charge disproportionation in BBO[4], though X-ray and resonant photoemission spectroscopy studies have not shown clear evidence for the same in BBO and the doped compounds [9,10]. The results are understood as due to very small charge transfer between the unequal Bi sites [5]. The crystal structure also evolves with doping and at room temperature, for x = 0.0 -0.1 it is monoclinic, from x = 0.1 to 0.3 it is orthorhombic and above x = 0.3 up to 0.5( = the solubility limit), it is cubic [11].In this work we study the elect...

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confidence: 93%

mentioning

confidence: 94%

Electron-phonon coupling induced pseudogap and the superconducting transition inBa0.67K0.33BiO
Chainani
¹
,
Yokoya
²
,
Shin
³

et al. 2001
Phys. Rev. B
30
3
19
0
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“…8 Ba 1−x K x BiO 3 (BKBO) crystallizes in the nominally simple cubic perovskite structure in the superconducting composition range 0.375 < x < 0.5 without any evidence of a breathing mode distortion, suggesting that simple cubic symmetry is preferred for the superconductivity. 9 A more recent report, however, claims tetragonal symmetry for BKBO, the distortion arising from rotations of the octahedra. 10 This is consistent with the structure of the Pb doped version.…”

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confidence: 99%

Lone Pair Effect, Structural Distortions, and Potential for Superconductivity in Tl Perovskites

Schoop

Müchler²,

Felser

et al. 2013

Inorg. Chem.

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Drawing the analogy to BaBiO3, we investigate via ab-initio electronic structure calculations potential new superconductors of the type ATlX3 with A = Rb, Cs and X = F, Cl, and Br, with a particular emphasis on RbTlCl3. Based on chemical reasoning, supported by the calculations, we show that Tl-based perovskites have structural and charge instabilities driven by the lone pair effect, similar to the case of BaBiO3, effectively becoming A2Tl 1+ Tl 3+ X6. We find that upon hole doping of RbTlCl3, structures without Tl 1+ , Tl 3+ charge disproportionation become more stable, although the ideal cubic perovskite, often viewed as the best host for superconductivity, should not be the most stable phase in the system. The known superconductor (Sr,K)BiO3 and hole doped RbTlCl3, predicted to be most stable in the same tetragonal structure, display highly analogous calculated electronic band structures.

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“…1.6. The highest superconducting transition temperature Tc =30 K is observed for x=0.4 [Pei 1990]. were semiconducting.…”

Section: Superconductivity In Baixkxbi03mentioning

confidence: 99%

“…The experimentally determined isotope effect coefficient a varied from 0.41±0.03 to 0.23±0.03 [Batiogg 1988, Hinks 1988, Kondoh 1989]. Although there is some square symbols are shown, zero resistance was not reached at any temperature above 10 K (after [Pei 1990] [Kondoh 1989, Uemura 1988. A CDW (Charge-Density-Wave) induced distortion is observed for the parent semiconductor, BaBiOs [Cox 1976[Cox ,1979, The K doping induces a insulator-metal phase transition.…”

Section: Superconductivity In Baixkxbi03mentioning

confidence: 99%

Photoemission study of some novel materials: rare earth/transition metal interface, Ba06K04BiO3 and AlPdMn

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This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer.The quality of this reproduction is dependent upon the quali^ of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproductioaIn the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note wiU indicate the deletion.Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book.

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Structural phase diagram of theBa1−xK

Cited by 400 publications

References 39 publications

Electron-phonon coupling induced pseudogap and the superconducting transition inBa0.67K0.33BiO
Chainani
¹
,
Yokoya
²
,
Shin
³

et al. 2001
Phys. Rev. B
30
3
19
0
View full text Add to dashboard Cite

Electron-phonon coupling induced pseudogap and the superconducting transition inBa0.67K0.33BiO
Chainani
¹
,
Yokoya
²
,
Shin
³

et al. 2001
Phys. Rev. B
30
3
19
0
View full text Add to dashboard Cite

Lone Pair Effect, Structural Distortions, and Potential for Superconductivity in Tl Perovskites

Photoemission study of some novel materials: rare earth/transition metal interface, Ba06K04BiO3 and AlPdMn

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Structural phase diagram of theBa1−xK

Cited by 400 publications

References 39 publications

Electron-phonon coupling induced pseudogap and the superconducting transition inBa0.67K0.33BiOChainani1, Yokoya2, Shin3 et al. 2001Phys. Rev. B303190View full textAdd to dashboardCite

Electron-phonon coupling induced pseudogap and the superconducting transition inBa0.67K0.33BiOChainani1, Yokoya2, Shin3 et al. 2001Phys. Rev. B303190View full textAdd to dashboardCite

Lone Pair Effect, Structural Distortions, and Potential for Superconductivity in Tl Perovskites

Photoemission study of some novel materials: rare earth/transition metal interface, Ba06K04BiO3 and AlPdMn

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Electron-phonon coupling induced pseudogap and the superconducting transition inBa0.67K0.33BiO
Chainani
¹
,
Yokoya
²
,
Shin
³

et al. 2001
Phys. Rev. B
30
3
19
0
View full text Add to dashboard Cite

Electron-phonon coupling induced pseudogap and the superconducting transition inBa0.67K0.33BiO
Chainani
¹
,
Yokoya
²
,
Shin
³

et al. 2001
Phys. Rev. B
30
3
19
0
View full text Add to dashboard Cite