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Chow, K. H.; Jestädt, T; Blundell, S. J.; Dunsiger, S. R.; Hayes, W.; Hitti, B.; Green, M.A.; Kiefl, R. F.; Millburn, J. E.; Pattenden, P.A.; Pratt, F. L.; Rosseinsky, M. J.

doi:10.1023/a:1012642802506

Cited by 4 publications

(6 citation statements)

References 15 publications

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“…69 [815]. More recent µSR experiments [816] have found onsets of magnetic ordered states at considerably higher temperatures, throughout the doping range 0.4 ≤ x ≤ 1.2, with a local maximum at x = 0.5 (open squares in Fig. 69).…”

Section: La2−xsrxnio4 (Lsno)mentioning

confidence: 95%

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

369

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: La2−xsrxnio4 (Lsno)mentioning

confidence: 95%

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

369

280

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“…In order to arrive at possible muon sites in La 2Ϫx Sr x NiO 4ϩ␦ , we have performed dipole field calculations, analogous to those described elsewhere. 39,40 The local magnetic field B (r ) sensed by the muon is given by the sum of the dipolar field B dip (r ), due to Ni moments and the hyperfine field B hf (r ), due to any nonzero electron spin density at the muon site. Although we lack knowledge of the hyperfine coupling constant it is assumed to be small, as in the case 39 of La 2 CuO 4 and other magnetic oxides.…”

Section: Muon Sitementioning

confidence: 99%

Temperature and doping-level dependence of magnetic order inLa2−xSrx
Jestädt
¹
,
Chow
²
,
Blundell
³

et al. 1999
Phys. Rev. B
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We report muon-spin-rotation (SR͒ measurements on a series of compounds with composition La 2Ϫx Sr x NiO 4ϩ␦ with strontium doping level x between 0 and 1. A magnetic transition is found in all the samples studied, which occurs at a composition-dependent temperature, T M . Below T M clear precession signals are observed in zero applied magnetic field for all x, indicating the existence of at least short-range magnetic order on a time scale longer than 10 Ϫ8 s. Above T M the magnetic correlation times decrease by several orders of magnitude. At xϷ0.33, we find peaks in both T M and the zero-temperature staggered magnetization, an observation which we attribute to the higher degree of localization of the holes at this doping level. The measurements of T M as a function of x extend the determination of Néel temperatures by previous neutron diffraction and SR measurements.

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“…The electronic properties of the intermediate phases are intriguings"charge ordering" transitions in which polaronic carriers are localized in superlattice arrays occur at a variety of temperatures in a narrow concentration range around x ) 0.33, 7,8 and the low-temperature dc magnetization of the insulating phases is characteristic of spin glasses, while complex magnetic structures involving "stripe" ordering are seen by neutron diffraction and µSR reveals reduced spin freezing temperatures. 1,2,5 Introduction of Ni III by oxidation is expected to produce magnetic interactions that will compete with the antiferromagnetic ground state of La 2 NiO 4 .…”

Section: Introductionmentioning

confidence: 99%

“…The Ni II /Ni III La 2 - x Sr x NiO 4 ±δ oxides with the K 2 NiF 4 structure have been the focus of much recent research. − Much higher doping levels are required to induce metal−insulator transitions in the nickel system than in the analogous cuprates, La 2 - x Sr x CuO 4 ±δ , with truly metallic behavior occurring only at nickel oxidation states higher than +III. The electronic properties of the intermediate phases are intriguing“charge ordering” transitions in which polaronic carriers are localized in superlattice arrays occur at a variety of temperatures in a narrow concentration range around x = 0.33, , and the low-temperature dc magnetization of the insulating phases is characteristic of spin glasses, while complex magnetic structures involving “stripe” ordering are seen by neutron diffraction and μSR reveals reduced spin freezing temperatures. ,, Introduction of Ni III by oxidation is expected to produce magnetic interactions that will compete with the antiferromagnetic ground state of La 2 NiO 4 .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

LaSrCr_xNi₁_-_xO₄₊_δ: Crystal Chemistry, Magnetism, and the Stabilization of Ni^I in an Oxide Environment

Millburn

Rosseinsky

1997

Chem. Mater.

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Magnetic, structural and reduction data on the K 2 NiF 4 structure Cr III /Ni III oxides, LaSrCr x Ni 1-x O 4+δ (0.1 e x e 0.9, where δ may be negative) are reported; samples with x > 0.2 adopt the tetragonal I4/mmm space group, while for x e 0.2, the samples are multiphasic due to competition between a novel vacancy-ordered Immm structure and the undistorted K 2 NiF 4 phase. Magnetic studies in the temperature range 5 e T/K e 300 show spin glass behavior for x < 0.9, with freezing temperatures of between 12 and 16 K: at higher temperature the susceptibilities display Curie-Weiss behavior. The magnetism of the x ) 0.9 sample resembles that reported for LaSrCrO 4 , displaying an antiferromagnetic transition at 150 K and weak ferromagnetism below 130 K. Reduction of the title compounds in 1 atm of flowing H 2 at ∼500 °C produces stable, oxygen-deficient compounds, notably La 2 Sr 2 -CrNiO 7 , which contains Ni I with a thermal stability unprecedented in an oxide.

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Untitled

Cited by 4 publications

References 15 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

Temperature and doping-level dependence of magnetic order inLa2−xSrx
Jestädt
¹
,
Chow
²
,
Blundell
³

et al. 1999
Phys. Rev. B
Self Cite

LaSrCr_xNi₁_-_xO₄₊_δ: Crystal Chemistry, Magnetism, and the Stabilization of Ni^I in an Oxide Environment

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Untitled

Cited by 4 publications

References 15 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

Temperature and doping-level dependence of magnetic order inLa2−xSrxJestädt1, Chow2, Blundell3 et al. 1999Phys. Rev. BSelf Cite

LaSrCrxNi1-xO4+δ: Crystal Chemistry, Magnetism, and the Stabilization of NiI in an Oxide Environment

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Product

Resources

About

Temperature and doping-level dependence of magnetic order inLa2−xSrx
Jestädt
¹
,
Chow
²
,
Blundell
³

et al. 1999
Phys. Rev. B
Self Cite

LaSrCr_xNi₁_-_xO₄₊_δ: Crystal Chemistry, Magnetism, and the Stabilization of Ni^I in an Oxide Environment