Giant<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>O</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>16</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow><mml:mi>−</mml:mi><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>O</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>18</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>Isotope Effect

Medarde, M.; Lacorre, P.; Conder, K.; Fauth, François; Fürrer, A.

doi:10.1103/physrevlett.80.2397

Cited by 151 publications

(96 citation statements)

References 23 publications

(27 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The number of 2p holes N h p at the oxygen sites are plotted as functions of ∆ in Fig. 3(b) [16] indicating that the electron-lattice coupling is important in RNiO 3 . Very recently, Alonso et al performed neutron diffraction studies of YNiO 3 and found the breathing-type distortion which may be an indication of charge ordering [17].…”

mentioning

confidence: 99%

See 1 more Smart Citation

Spin and charge ordering in self-doped Mott insulators

Mizokawa¹,

Khomskii²,

Sawatzky³

2000

Phys. Rev. B

214

210

View full text Add to dashboard Cite

We have investigated possible spin and charge ordered states in 3d transition-metal oxides with small or negative charge-transfer energy, which can be regarded as self-doped Mott insulators, using Hartree-Fock calculations on d-p-type lattice models. It was found that an antiferromagnetic state with charge ordering in oxygen 2p orbitals is favored for relatively large charge-transfer energy and may be relevant for PrNiO3 and NdNiO3. On the other hand, an antiferromagnetic state with charge ordering in transition-metal 3d orbitals tends to be stable for highly negative charge-transfer energy and can be stabilized by the breathing-type lattice distortion; this is probably realized in YNiO3.The electronic structure of 3d transition metal oxides is described by Zaanen-Sawatzky-Allen (ZSA) scheme [1] in which they are classified into two regimes according to the relative magnitude of the oxygen-to-metal chargetransfer energy ∆ and the d − d Coulomb interaction energy U . While the magnitude of the band gap is given by U in the Mott-Hubbard regime, it is given by ∆ in the charge-transfer regime ∆ < U . 3d transition-metal oxides with high valence generally have very small or negative charge-transfer energy ∆ and fall in a region which is not included in the ZSA scheme [2]. Actually, perovskitetype 3d transition-metal oxides such as LaCuhave been studied by high energy spectroscopy and have been found to have very small or even negative charge-transfer energy ∆.With small or negative ∆, the highest part of the oxygen 2p bands can overlap with the lowest part of the upper Hubbard band constructed from the transition-metal 3d orbitals so that some holes are transferred from the 3d orbitals to the 2p orbitals in the ground state. This state can be viewed as a self-doped state of a Mott insulator [6] such as has recently been suggested for CrO 2 [7]. The properties of such system are far from clear and can be very rich. It can be a paramagnetic metal, a ferromagnetic (FM) metal, and a non-magnetic insulator similar to . However, there exists another possibility which has not been explored until now: it may have charge ordering or charge density wave. It is possible that, in a self-doped state of a Mott insulator, holes in the oxygen 2p orbitals undergo charge ordering just like doped Mott insulators such as La 2−x Sr x NiO 4 [8]. In this letter, we study this possibility using model HartreeFock (HF) calculation and show that spin and charge ordered states may appear in perovskites with negative ∆. Based on the calculations, we argue that this phenomena occurs in perovskites containing Fe 4+ (CaFeO 3 ) [9] and Ni 3+ (RNiO 3 where R is a rare earth) [10]. Specifically, we consider the latter system, properties of which, especially its strange magnetic properties remain a puzzle until now [4,11].We use the multi-band d-p model with 16 Ni sites in which full degeneracy of the Ni 3d orbitals and the oxygen 2p orbitals are taken into account [12]. The Hamiltonian is given byd + i,mσ are creation operators for the 3d electrons at...

show abstract

mentioning

confidence: 99%

“…We use the multi-band d-p model with 16 Ni sites in which full degeneracy of the Ni 3d orbitals and the oxygen 2p orbitals are taken into account [12]. The Hamiltonian is given by…”

mentioning

confidence: 99%

Spin and charge ordering in self-doped Mott insulators

Mizokawa¹,

Khomskii²,

Sawatzky³

2000

Phys. Rev. B

214

210

View full text Add to dashboard Cite

show abstract

“…18 O-substitution increases the transition temperature T MI but the shift of the T MI is rather small in comparison to that observed in manganates and nickelates [12,13]. Measurements of the reverse susceptibility can suggest that a spin state transition can be an origin of the metalinsulator transition.…”

Section: Oxygen Isotope Effectmentioning

confidence: 99%

Layered Cobaltites: Synthesis, Oxygen Nonstoichiometry, Transport and Magnetic Properties

et al. 2007

Self Cite

View full text Add to dashboard Cite

Complex cobalt oxide perovskite-derived compounds with a general formula LnBaCo2O5+x (Ln = rare earth) attracted considerable interests because of their interesting properties: magnetic and metal-insulator transitions, giant magnetoresistance, ionic conductivity, and a structural similarity to high temperature superconductors. All the compounds are oxygen nonstoichiometric (0 < x < 1) and the cobalt cations can adopt different oxidation and spin states. Compounds with x ≈ 0.5 display a metal-insulator transition. We found that this transition is affected by an oxygen isotope substitution and is accompanied by structural changes and melting of the orbital ordering. Studies of the metal-insulator transition qualitatively support the models assuming rather carriers delocalization than a spin-state transition in Co 3+ .

show abstract

“…Além disso, Obradors et al [19] investigaram a dependência de T M I com P, para as amostras cerâmicas de N dN iO 3 Entretanto, Zhou et al [17] argumentam que o fator relevante modicado sob pressão não é o ângulo de inclinação φ, ou analogamente, o fator de tolerância t. No trabalho de Zhou, a largura de banda é proposta segundo um modelo polarônico como sendo W = W b exp(−λε p /hω 0 ), onde W b é a largura de banda no modelo de Holstein e ω 0 é a frequência de vibração dos átomos de O. Assim, o comportamento da resistividade elétrica sob pressão é explicado em termos da diminuição nas distâncias Ni-O, que levaria a um aumento em ω 0 , tendo como consequência um aumento em W . Esse modelo de largura de banda aplicado aos niquelatos foi inicialmente proposto para explicar um aumento de 10 K em T M I pela substituição isotópica do oxigênio 16 O → 18 O, isto é, sem nenhuma alteração em t ou φ [16]. Esses resultados, juntamente com a desproporção de carga nos compostos Y N iO 3 , são indicativos de que o mecanismo responsável pela transição envolve fortes interações do tipo elétron-rede [16,36], sugerindo que a transição MI ocorre devido a efeitos Jahn-Teller, juntamente com a formação de pôlarons.…”

Section: Estrutura Cristalinaunclassified

“…Esse modelo de largura de banda aplicado aos niquelatos foi inicialmente proposto para explicar um aumento de 10 K em T M I pela substituição isotópica do oxigênio 16 O → 18 O, isto é, sem nenhuma alteração em t ou φ [16]. Esses resultados, juntamente com a desproporção de carga nos compostos Y N iO 3 , são indicativos de que o mecanismo responsável pela transição envolve fortes interações do tipo elétron-rede [16,36], sugerindo que a transição MI ocorre devido a efeitos Jahn-Teller, juntamente com a formação de pôlarons. No entanto, a formação de pôlarons requer a presença de N i 2+ e N i 3+ .…”

Section: Estrutura Cristalinaunclassified

Medidas de transporte sob pressão em materiais cerâmicos

Andrade¹

View full text Add to dashboard Cite

GiantO16−O18Isotope Effect

Cited by 151 publications

References 23 publications

Spin and charge ordering in self-doped Mott insulators

Spin and charge ordering in self-doped Mott insulators

Layered Cobaltites: Synthesis, Oxygen Nonstoichiometry, Transport and Magnetic Properties

Medidas de transporte sob pressão em materiais cerâmicos

Contact Info

Product

Resources

About