Hole doping in La2−xBaxCuO4−y using oxygen stoichiometry

Moodenbaugh, A. R.; Wildgruber, U.; Wang, Y.L.; Xu, Youwen

doi:10.1016/0921-4534(95)00112-3

Cited by 10 publications

(6 citation statements)

References 18 publications

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“…Double doping experiments [889] have demonstrated that the T c suppression occurs at a fixed hole content x, and does not depend on, e.g., Ba concentration. Similar results are found in LBCO, by introducing oxygen defects (i.e., δ < 0, which occur predominantly in the CuO 2 planes) [890,891]. Again, the largest T c suppression occurs when P ≈ x+2δ = 0.125, but as |δ| increases, so does the value of this minimum T c .…”

Section: B Ltt Phase As a Striped Phasesupporting

confidence: 75%

A survey of the Van Hove scenario for high-tc superconductivity with special emphasis on pseudogaps and striped phases

Markiewicz

1997

Journal of Physics and Chemistry of Solids

371

280

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The Van Hove singularity (VHS) provides a paradigm for the study of the role of peaks in the density of states (dos) on electronic properties. More importantly, it appears to play a major role in the physics of the high-Tc superconductors, particularly since recent photoemission studies have found that the VHS is close to the Fermi level in most of the high-Tc cuprates near the composition of optimum Tc. This paper offers a comprehensive survey of the VHS model, describing both theoretical properties and experimental evidence for the picture. Special topics discussed include a survey of the Fermi surfaces of the cuprates and related compounds, and an analysis of the reliability of the slave boson approach to correlation effects. While many properties of the cuprates can be qualitatively understood by a simple rigid-band-filling model, this is inadequate for more quantitative results, since correlation effects tend to pin the Fermi level near the VHS over an extended doping range, and can lead to a nanoscale phase separation. Furthermore, the peaks in the dos lead to competition from other instabilities, both magnetic and structural (related to charge density waves). A novel form of dynamic structural instability, involving dynamic VHS-Jahn-Teller effects has been predicted. Scattered through the literature, there is considerable experimental evidence for both nanoscale phase separation of holes, and for local, possibly dynamic, structural disorder. This review attempts to gather these results into a comprehensive database, to sort the results, and to see how they fit into the Van Hove scenario. Recent experiments on underdoped cuprates are found to provide a strong confirmation that the pseudogap is driven by a splitting of the VHS degeneracy.

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Section: B Ltt Phase As a Striped Phasesupporting

confidence: 75%

A survey of the Van Hove scenario for high-tc superconductivity with special emphasis on pseudogaps and striped phases

Markiewicz

1997

Journal of Physics and Chemistry of Solids

371

280

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“…It is observed that, despite the increase in net dopant content, the magnetic and superconducting anomalies remain closely anchored to the hole content of 1/8. A similar result more recently has been secured by employing LBCO samples loaded under pressure to various excess oxygen stoichiometries [25].…”

Section: Background To the 'Stripe Phase' Formation And To The 'One-e...supporting

confidence: 68%

The position of the `one-eighth' anomaly within the high-temperature superconductivity problem: matters concerning stripes and domains, Jahn-Teller effect and negative-Ubehaviour

Wilson¹

1998

J. Phys.: Condens. Matter

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The subject of mixed-valence charge segregation in HTSC materials is further examined. The self-organized microstructural details are explored including 1D/2D crossover. Neutron and extended x-ray absorption fine-structure results provide the basis for this analysis. The Jahn-Teller effect is seen as a crucial element in the `charge/spin'-separation structuring. On cooling, the emergent resonating-valence-bond-type magnetic organization of the divalent subsystem assists greatly in preparing (if not pre-pairing) the overall system for high-temperature superconductivity. Under the action of the negative-U centres of the high-valence subsystem established in the domain boundaries, the system can evolve naturally with doping and cooling from towards greater s-wave-type content of the HTSC order parameter.

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“…Oxygen reduction ͑which removes two holes per oxygen atom͒ in La 2Ϫx Ba x CuO 4Ϫy and Thorium doping ͑which removes one hole per Th atom͒ in La 2ϪxϪz Th z Ba x CuO 4 show that the sharp suppression of superconductivity depends on doping and is centered about the critical-hole concentration of h c ϭxϪ2yϭxϪzϷ0.125. 8,9 Whereas it is clear from an experimental standpoint that both h c ϳ0.125 and an underlying LTT phase result in enhanced hole-lattice coupling and effectively reduce T c , quite physically distinct mechanisms are suggested to explain the observed T c suppression.…”

Section: Introductionmentioning

confidence: 99%

XAFS study of the low-temperature tetragonal phase ofLa2−xBaxCuO
Haskel
¹
,
Stern
²
,
Doğan
³

et al. 2000
Phys. Rev. B
52
7
44
0
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Angular dependent x-ray absorption fine structure ͑XAFS͒ measurements of all La, Ba, and Cu sites determined the origin and nature of the intrinsic disorder present in the low temperature tetragonal ͑LTT͒ structural ground state of La 2Ϫx Ba x CuO 4 with xϭ0.125,0.15 at Tϭ10 K. Ba doping induces major local distortions that extend as far as 5 Å from its lattice site. Despite the low Ba content the large distortions significantly affect the XAFS of the majority La and Cu sites. The distribution of the local LTT tilt angle of CuO 6 octahedra was directly determined from single and multiple scattering contributions to the XAFS of La and Cu sites. This angle, which regulates the strength of electron-lattice and spin-spin coupling in this material, was found to exhibit large, random fluctuations with rms ͓͗(Ϫ͗͘) 2 ͔͘ 1/2 Ϸ2͗͘, ͗͘ being the average tilt angle determined by diffraction techniques. These fluctuations originate in the large, random, static disorder introduced with Ba doping. Their presence has implications for the plausibility of a mobility gap causing T c suppression at xϭ0.125 in only the LTT phase, and for the correlation length of the postulated charge and spin stripes.

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Hole doping in La2−xBaxCuO4−y using oxygen stoichiometry

Cited by 10 publications

References 18 publications

A survey of the Van Hove scenario for high-tc superconductivity with special emphasis on pseudogaps and striped phases

A survey of the Van Hove scenario for high-tc superconductivity with special emphasis on pseudogaps and striped phases

The position of the `one-eighth' anomaly within the high-temperature superconductivity problem: matters concerning stripes and domains, Jahn-Teller effect and negative-Ubehaviour

XAFS study of the low-temperature tetragonal phase ofLa2−xBaxCuO
Haskel
¹
,
Stern
²
,
Doğan
³

et al. 2000
Phys. Rev. B
52
7
44
0
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Hole doping in La2−xBaxCuO4−y using oxygen stoichiometry

Cited by 10 publications

References 18 publications

A survey of the Van Hove scenario for high-tc superconductivity with special emphasis on pseudogaps and striped phases

A survey of the Van Hove scenario for high-tc superconductivity with special emphasis on pseudogaps and striped phases

The position of the `one-eighth' anomaly within the high-temperature superconductivity problem: matters concerning stripes and domains, Jahn-Teller effect and negative-Ubehaviour

XAFS study of the low-temperature tetragonal phase ofLa2−xBaxCuOHaskel1, Stern2, Doğan3 et al. 2000Phys. Rev. B527440View full textAdd to dashboardCite

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About

XAFS study of the low-temperature tetragonal phase ofLa2−xBaxCuO
Haskel
¹
,
Stern
²
,
Doğan
³

et al. 2000
Phys. Rev. B
52
7
44
0
View full text Add to dashboard Cite