Room temperature topotactic oxidation of lanthanum cobalt oxide La2CoO4.0

Nemudry, A. P.

doi:10.1016/s0167-2738(98)00105-2

Cited by 35 publications

(32 citation statements)

References 22 publications

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“…The possible spin-state transitions as a function of doping render the analysis of the phase diagram of La 2−x Sr x CoO 4 more difficult and different spin-state scenarios were proposed [121,127]. Similar to the nickelates, the layered cobaltates also tend to incorporate large amounts of excess oxygen rendering the growth of single crystals particularly difficult in the low-doping range [128][129][130][131] whereas powder samples can be more easily controlled [121,132].…”

Section: Incommensurate Magnetic Order In Layered Cobaltatesmentioning

confidence: 99%

Neutron scattering studies on stripe phases in non-cuprate materials

Ulbrich

Braden

2012

Physica C: Superconductivity

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Several non-cuprates layered transition-metal oxides exhibit clear evidence for stripe ordering of charges and magnetic moments. Therefore, stripe order should be considered as the typical consequence of doping a Mott insulator, but only in cuprates stripe order or fluctuating stripes coexist with metallic properties. A linear relationship between the charge concentration and the incommensurate structural and magnetic modulations can be considered as the finger print of stripe ordering with localized degrees of freedom. In nickelates and in cobaltates with K 2 NiF 4 structure, doping suppresses the nearest-neighbor antiferromagnetism and induces stripe order. The higher amount of doping needed to induce stripe phases in these non-cuprates series can be attributed to reduced charge mobility. Also manganites exhibit clear evidence for stripe phases with further enhanced complexity, because orbital degrees of freedom are involved. Orbital ordering is the key element of stripe order in manganites since it is associated with the strongest structural distortion and with the perfectly fulfilled relation between doping and incommensurability. Magnetic excitations in insulating stripe phases exhibit strong similarity with those in the cuprates, but only for sufficiently short magnetic correlation lengths reflecting well-defined magnetic stripes that are only loosely coupled.

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Section: Incommensurate Magnetic Order In Layered Cobaltatesmentioning

confidence: 99%

Neutron scattering studies on stripe phases in non-cuprate materials

Ulbrich

Braden

2012

Physica C: Superconductivity

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“…Such crystals have a tendency for excess oxygen when x 0.3, similar to the La 2−x Sr x NiO 4+δ system [11][12][13][14]. On this basis we expect that the lowest doped samples have δ > 0, but approach oxygen stoichiometry by x ≈ 0.3.…”

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confidence: 91%

Magnetic phase diagram ofLa2−xSrxCoO4revised using muon-spin relaxation

et al. 2016

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We report the results of a muon-spin relaxation (μSR) investigation of La 2−x Sr x CoO 4 , an antiferromagnetic insulating series which has been shown to support charge ordered and magnetic stripe phases and an hourglass magnetic excitation spectrum. We present a revised magnetic phase diagram, which shows that the suppression of the magnetic ordering temperature is highly sensitive to small concentrations of holes. Distinct behavior within an intermediate x range (0.2 x 0.6) suggests that the putative stripe ordered phase extends to lower x than previously thought. Further charge doping (0.67 x 0.9) prevents magnetic ordering for T 1.5 K.DOI: 10.1103/PhysRevB.93.140406Thirty years after the discovery of high-T c superconductivity, the role of multiple order parameters in the cuprates continues to be a topic of intense research, with the interplay between correlations of charge order (CO), antiferromagnetic spin order (SO), and superconductivity the topic of much investigation [1][2][3][4][5]. Although a detailed comparison of specific systems has been found to be problematical, in order to elucidate the details of the physics at play in a different context it is illuminating to study isostructural nonsuperconducting 3d transition metal oxides [6] such as the antiferromagnetic series La 2−x Sr x CoO 4 (LSCO). Controlled doping of holes into the two-dimensional CoO 2 layers is achieved via substitution of Sr for La but, in contrast to the cuprates, a spin-blockade mechanism means the series remains an insulator for x 1 [7]. The previously reported phase diagram of LSCO, determined by neutron scattering [8], shows a region of nearest-neighbor antiferromagnetism (nnAFM) for low dopant concentrations (x 0.3) and incommensurate (IC) magnetism consistent with stripelike CO and SOs for an intermediate doping range 0.3 x 0.6. Recently, muon-spin rotation (μSR) and NMR measurements made on the stripe ordered x = 1/3 compound [9] revealed the importance of a range of time scales in the magnetic ordering of the material, with μSR showing both the onset of static magnetic order and the freezing of dynamical processes at temperatures significantly lower than the ordering temperature previously identified using neutrons. This is because μSR is sensitive to fluctuations on the microsecond time scale (set by the muon gyromagnetic ratio γ μ = 2π × 135.5 MHz T −1 ). Such slow fluctuations appear static in neutron scattering measurements where the energy resolution E ≈ 1 meV constrains the sensitivity of the technique to fluctuations with a much faster time scale

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“…The amount of NO x produced can be determined, as shown in [250], with high accuracy by the chemiluminescence technique, which has high sensitivity and good selectivity. In [279], another principle of measuring the partial pressure was used Ð thermogravimetric analysis based on measuring the changes in the weight of a membrane made of La 1Àx Sr x Co 1Ày Fe y O 3Àd as a result of desorption or adsorption of oxygen. The high sensitivity of the method has been confirmed.…”

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confidence: 99%

Specific features of spin, charge, and orbital ordering in cobaltites

Ivanovа¹,

Овчинников²,

Korshunov³

et al. 2009

Phys.-Usp.

126

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Complex cobalt oxides known as cobaltites are reviewed, including LnCoO 3 -based perovskite-structured rare-earth cobaltites (where Ln is lanthanum or a lantha-nide), quasi-two-dimensional and quasi-one-dimensional cobaltites of the types LnCo 2 O 5d , La 2 CoO 4 , and Ca 3 Co 2 O 8 , and Na x CoO 2 Á yH 2 O superconducting compounds. Key experimental and theoretical results are presented, with emphasis on the interplay between charge, spin, and orbital degrees of freedom. Two problems of specific relevance to cobaltites Ð the spin state instability of Co 3 ions in LnCoO 3 , and the nature of superconductivity in Na x CoO 2 Á yH 2 O Ð are also given significant attention.

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Room temperature topotactic oxidation of lanthanum cobalt oxide La2CoO4.0

Cited by 35 publications

References 22 publications

Neutron scattering studies on stripe phases in non-cuprate materials

Neutron scattering studies on stripe phases in non-cuprate materials

Magnetic phase diagram ofLa2−xSrxCoO4revised using muon-spin relaxation

Specific features of spin, charge, and orbital ordering in cobaltites

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