Magnetism and unusual Cu valency in quadruple perovskites

Alippi, Paola; Fiorentini, Vincenzo

doi:10.1140/epjb/e2012-21067-6

Cited by 11 publications

(5 citation statements)

References 31 publications

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“…The difference in total energies at different magnetic structures, which are obtained by subtracting the G-AFM energy at U Fe = 4 eV and U Cu = 5 eV, are given in Table . As can be seen in Table , the G_AFM spin arrangement for Fe atoms is energetically favorable and is the magnetic ground state of LaCFO, which agrees well with the experimental and theoretical results. ,, Interestingly, the G_AFM configuration at U Fe = 4 eV and U Cu = 5 eV is the most stable state in all pairs of U values, and the corresponding lattice parameter ( a ) is the closest to the experimental value . Therefore, we adopt the G_AFM magnetic structure with U Fe = 4 eV and U Cu = 5 eV in the following calculations for the ground state properties of LaCFO perovskite.…”

Section: Resultssupporting

confidence: 79%

Theoretical Study on the Negative Thermal Expansion Perovskite LaCu₃Fe₄O₁₂: Pressure-Triggered Transition of Magnetism, Charge, and Spin State

et al. 2017

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The A-site ordered negative thermal expansion material LaCuFeO (LaCFO) was comprehensively investigated by using first-principles calculations. A pressure-triggered crystal structural phase transition from space group Im3̅ (No. 204) to Pn3̅ (No. 201) and magnetic transformation from a G-type antiferromagnetic (G_AFM) ground state to ferrimagnetic (FerriM) coupling were observed in LaCFO via gradual compression of the equilibrium volume. Correspondingly, the Fe-Cu intersite charge transfer from Fe to Cu 3d orbital, expressed as 4Fe + 3Cu → 4Fe + 3Cu, was simulated along with the magnetic phase transformation from the G_AFM configuration to the FerriM state. Intriguingly, the Fe charge disproportionation, formulated as 8Fe → 5Fe + 3Fe, appeared and was attributed to the strong hybridization between Fe 3d and O 2p orbitals in the FerriM state when the volumes were substantially compressed up to less than or equal to 80%V. Meanwhile, the external hydrostatic pressure also leads to a spin flip from a high-spin Fe antiferromagnetically arranged LaCuFeO Mott insulator at low pressure and goes through a FerriM LaCuFeO half-metal to a low-spin FerriM coupled LaCuFeFeO metal at high pressure. Therefore, the crossover from high spin to low spin is responsible for the charge disproportionation in LaCFO. Essentially, the charge transfer and spin flip originate from the discontinuous changes of metal-oxygen bond lengths and angles in the compressed atomic structure. Finally, the negative thermal expansion behavior and mechanism of LaCFO were theoretically examined and clearly revealed.

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Section: Resultssupporting

confidence: 79%

Theoretical Study on the Negative Thermal Expansion Perovskite LaCu₃Fe₄O₁₂: Pressure-Triggered Transition of Magnetism, Charge, and Spin State

et al. 2017

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“…Since we are dealing with a titanate that is strongly characterized by cuprate-like electronic features [36], it is appropriate to recall the solid success record of VPSIC on the electronic and structural properties of Cu oxides of various composition and dimensionality. It describes correctly the magnetic and insulating (anywhere from semiconducting to high-insulator) character of YBa 2 Cu 3 O 6 [7], monoclinic CuO [22], GeCuO 3 [37], and Ca-doped YCuO cuprate [38], all of which are metals and nonmagnetic in GGA or LDA.…”

Section: B Discussionmentioning

confidence: 99%

Multigap absorption inCaCu3Ti4O12and the prediction capability ofab initiomethods

et al. 2014

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We report the electronic properties of the quadruple perovskite CaCu 3 Ti 4 O 12 as obtained via several densityfunctional based methods and propose a new interpretation of optical experiments to the effect that four distinct transitions (centered around 0.7, 1.5, 2.5, and 3.5 eV) contribute to the spectrum. The comparison with experiment is satisfactory, especially after we account for the effects of spin disorder, which does not close the fundamental gap but suppresses the transition intensity. We find that some of the methods we employ tend to overestimate considerably the gaps for standard values of the respective adjustable parameters.

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“…1(a)). In this structure, a surprisingly rich set of interesting physics phenomena10111213141516 have been demonstrated by replacement of the B-site 3 d transition metal ion via experiment and theory including colossal dielectric constant1718, ferrimagnetism19, charge, orbital, and spin ordering20, non-fermi liquid behavior21, enhanced electronic correlations22 and possibly the Zhang-Rice state23. In addition, previous reports hinted at the presence of a mixed-valency on Cu for B = Cr and Co2324.…”

mentioning

confidence: 90%

Zhang-Rice physics and anomalous copper states in A-site ordered perovskites

Meyers

Mukherjee

Cheng

et al. 2013

Sci Rep

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In low dimensional cuprates several interesting phenomena, including high Tc superconductivity, are deeply connected to electron correlations on Cu and the presence of the Zhang-Rice (ZR) singlet state. Here, we report on direct spectroscopic observation of the ZR state responsible for the low-energy physical properties in two isostructural A-site ordered cuprate perovskites, CaCu3Co4O12 and CaCu3Cr4O12 as revealed by resonant soft x-ray absorption spectroscopy on the Cu L3,2- and O K-edges. These measurements reveal the signature of Cu in the high-energy 3+ (3d8), the typical 2+ (3d9), as well as features of the ZR singlet state (i.e., 3d9L, L denotes an oxygen hole). First principles GGA + U calculations affirm that the B-site cation controls the degree of Cu-O hybridization and, thus, the Cu valency. These findings introduce another avenue for the study and manipulation of cuprates, bypassing the complexities inherent to conventional chemical doping (i.e. disorder) that hinder the relevant physics.

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Magnetism and unusual Cu valency in quadruple perovskites

Cited by 11 publications

References 31 publications

Theoretical Study on the Negative Thermal Expansion Perovskite LaCu₃Fe₄O₁₂: Pressure-Triggered Transition of Magnetism, Charge, and Spin State

Theoretical Study on the Negative Thermal Expansion Perovskite LaCu₃Fe₄O₁₂: Pressure-Triggered Transition of Magnetism, Charge, and Spin State

Multigap absorption inCaCu3Ti4O12and the prediction capability ofab initiomethods

Zhang-Rice physics and anomalous copper states in A-site ordered perovskites

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Magnetism and unusual Cu valency in quadruple perovskites

Cited by 11 publications

References 31 publications

Theoretical Study on the Negative Thermal Expansion Perovskite LaCu3Fe4O12: Pressure-Triggered Transition of Magnetism, Charge, and Spin State

Theoretical Study on the Negative Thermal Expansion Perovskite LaCu3Fe4O12: Pressure-Triggered Transition of Magnetism, Charge, and Spin State

Multigap absorption inCaCu3Ti4O12and the prediction capability ofab initiomethods

Zhang-Rice physics and anomalous copper states in A-site ordered perovskites

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Theoretical Study on the Negative Thermal Expansion Perovskite LaCu₃Fe₄O₁₂: Pressure-Triggered Transition of Magnetism, Charge, and Spin State

Theoretical Study on the Negative Thermal Expansion Perovskite LaCu₃Fe₄O₁₂: Pressure-Triggered Transition of Magnetism, Charge, and Spin State