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Johnston, D. C.; Johnson, Jack W.; Goshorn, D. P.; Jacobson, Allan J.

doi:10.1103/physrevb.35.219

Cited by 297 publications

(178 citation statements)

References 18 publications

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“…1 Of particular interest is the fact that each vanadium atom of VOPO is in the +4 oxidation state, leaving one unpaired electron in a 3d orbital. This leads to a particularly complex antiferromagnetic coupling and this has stimulated numerous experimental [2][3][4][5][6][7][8][9] and computational studies. [10][11][12][13][14] The magnetic structure of VOPO was first thought to be a Heisenberg spin- 1 2 ladder model.…”

Section: Introductionmentioning

confidence: 99%

The magnetic and electronic structure of vanadyl pyrophosphate from density functional theory

Cheng

Nielsen

Tahir-Kheli

et al. 2011

Phys. Chem. Chem. Phys.

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We have studied the magnetic structure of the high symmetry vanadyl pyrophosphate ((VO) 2 P 2 O 7 , VOPO), focusing on the spin exchange couplings, using density functional theory (B3LYP) with the full three-dimensional periodicity. VOPO involves four distinct spin couplings: two larger couplings exist along the chain direction (a-axis), which we predict to be antiferromagnetic, J OPO = À156.8 K and J O = À68.6 K, and two weaker couplings appear along the c (between two layers) and b directions (between two chains in the same layer), which we calculate to be ferromagnetic, J layer = 19.2 K and J chain = 2.8 K. Based on the local density of states and the response of spin couplings to varying the cell parameter a, we found that J OPO originates from a super-exchange interaction through the bridging -O-P-O-unit. In contrast, J O results from a direct overlap of 3d x 2 À y 2 orbitals on two vanadium atoms in the same V 2 O 8 motif, making it very sensitive to structural fluctuations. Based on the variations in V-O bond length as a function of strain along a, we found that the V-O bonds of V-(OPO) 2 -V are covalent and rigid, whereas the bonds of V-(O) 2 -V are fragile and dative. These distinctions suggest that compression along the a-axis would have a dramatic impact on J O , changing the magnetic structure and spin gap of VOPO. This result also suggests that assuming J O to be a constant over the range of 2-300 K whilst fitting couplings to the experimental magnetic susceptibility is an invalid method. Regarding its role as a catalyst, the bonding pattern suggests that O 2 can penetrate beyond the top layers of the VOPO surface, converting multiple V atoms from the +4 to +5 oxidation state, which seems crucial to explain the deep oxidation of n-butane to maleic anhydride.

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Section: Introductionmentioning

confidence: 99%

The magnetic and electronic structure of vanadyl pyrophosphate from density functional theory

Cheng

Nielsen

Tahir-Kheli

et al. 2011

Phys. Chem. Chem. Phys.

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“…Further investigations, including spectroscopic studies, might help to make clear the issue. Seen in Fig.6, a characteristic maximum expected from 1D antiferromagnetism in T vs χ plot for either BonnerFisher or spin-gap models was not observed at all, although the chains were substantially antiferromagnetic [14,15,16,17]. Below approximately 100 K, the inverse magnetic susceptibility gradually starts to apart from the CW line to go down on cooling, indicative of gradual growth of a ferromagnetic component in short range.…”

Section: Resultsmentioning

confidence: 99%

“…The c−axis constant (3.56251(9)Å) reflects the average of Co to Co distances in the chains; almost are close to ∼3.56Å, but few parts at ∼2.61Å may be somewhat involved. Since the oxygen-coordination environment of all cobalt atoms is not unique, a degree of magnetic uniformity of the present chain compound might be as low as that of the copper oxide Sr 5 Pb 3 CuO 12 , far rather than other well-studied spin-chain compounds [14,15,16,17].…”

Section: Resultsmentioning

confidence: 99%

Synthesis, Crystal Structure, and Magnetic Properties of the Linear-Chain Cobalt Oxide Sr5Pb3CoO12

Yamaura

Huang

Takayama‐Muromachi

2002

Journal of Solid State Chemistry

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The novel spin-chain cobalt oxide Sr5Pb3CoO12 [P62m, a = 10.1093(2)Å and c = 3.562 51(9)Å at 295 K] is reported. Polycrystalline sample of the compound was studied by neutron diffraction (at 6 and 295 K) and magnetic susceptibility measurements (5 to 390 K). The cobalt oxide was found to be analogous to the copper oxide Sr5Pb3CuO12, which is comprised of magnetic-linear chains at inter-chain distance of 10Å. Although the cobalt oxide chains (µ eff of 3.64 µB per Co) are substantially antiferromagnetic (θW = -38.8 K), neither low-dimensional magnetism nor long-range ordering has been found; a local-structure disorder in the chains might impact on the magnetism. This compound is highly electrically insulating.

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“…2). It is a spin system situated between one-dimensional (1D) and two-dimensional (2D) quantum magnets [13][14][15]. For all J R /J > 0, there is a gap in the spin excitation spectrum [16].…”

Section: Spin Laddermentioning

confidence: 99%

Low-temperature heat transport of spin-gapped quantum magnets

Zhao

Liu

et al. 2016

Sci. China Phys. Mech. Astron.

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This article reviews low-temperature heat transport studies of spin-gapped quantum magnets in the last few decades. Quantum magnets with small spins and low dimensionality exhibit a variety of novel phenomena. Among them, some systems are characteristic of having quantum-mechanism spin gap in their magnetic excitation spectra, including spin-Peierls systems, S = 1 Haldane chains, S = 1/2 spin ladders, and spin dimmers. In some particular spin-gapped systems, the XY-type antiferromagnetic state induced by magnetic field that closes the spin gap can be described as a magnon Bose-Einstein condensation (BEC). Heat transport is effective in probing the magnetic excitations and magnetic phase transitions, and has been extensively studied for the spin-gapped systems. A large and ballistic spin thermal conductivity was observed in the two-leg Heisenberg S = 1/2 ladder compounds. The characteristic of magnetic thermal transport of the Haldane chain systems is quite controversial on both the theoretical and experimental results. For the spin-Peierls system, the spin excitations can also act as heat carriers. In spin-dimer compounds, the magnetic excitations mainly play a role of scattering phonons. The magnetic excitations in the magnon BEC systems displayed dual roles, carrying heat or scattering phonons, in different materials.

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Magnetic susceptibility of (VO)2P2
D. C. Johnston
¹
,
Jack W. Johnson
²
,
D. P. Goshorn
³

et al.

Cited by 297 publications

References 18 publications

The magnetic and electronic structure of vanadyl pyrophosphate from density functional theory

The magnetic and electronic structure of vanadyl pyrophosphate from density functional theory

Synthesis, Crystal Structure, and Magnetic Properties of the Linear-Chain Cobalt Oxide Sr5Pb3CoO12

Low-temperature heat transport of spin-gapped quantum magnets

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Magnetic susceptibility of (VO)2P2D. C. Johnston1, Jack W. Johnson2, D. P. Goshorn3 et al.

Cited by 297 publications

References 18 publications

The magnetic and electronic structure of vanadyl pyrophosphate from density functional theory

The magnetic and electronic structure of vanadyl pyrophosphate from density functional theory

Synthesis, Crystal Structure, and Magnetic Properties of the Linear-Chain Cobalt Oxide Sr5Pb3CoO12

Low-temperature heat transport of spin-gapped quantum magnets

Contact Info

Product

Resources

About

Magnetic susceptibility of (VO)2P2
D. C. Johnston
¹
,
Jack W. Johnson
²
,
D. P. Goshorn
³

et al.