A thermal neutron investigation of magnetic correlations in liquid oxygen

Deraman, Mohamad; Dore, John C.; Schweizer, J.

doi:10.1016/0304-8853(85)90179-9

Cited by 22 publications

(14 citation statements)

References 14 publications

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“…For the "normal," lowtemperature, liquid phases diffraction data are available. 11,12 Very recently, an x-ray diffraction study of fluid oxygen has been reported for states between 357 K, 7.4 GPa and 750 K, 17.2 GPa; 13 unfortunately, the issue of orientational correlations has not been addressed there.…”

Section: Introductionmentioning

confidence: 98%

Orientational correlations in high-pressure fluid oxygen and nitrogen

et al. 2008

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High-pressure x-ray diffraction measurements for supercritical fluid oxygen at 0.9, 1.2, 4.3, and 5.2 GPa and for supercritical fluid nitrogen at 2.5 GPa have been carried out at room temperature by using synchrotron x-ray diffraction. The structure factors have been interpreted by means of the reverse Monte Carlo method. Site-site and center-center radial distribution functions and relative orientations of molecular axes as a function of distance between molecular centers have been calculated from the particle configurations. At distances below the position of the first maximum of the center-center radial distribution function, the dominance of parallel and "X-shaped" alignments of neighboring molecules has been revealed. Superfluid O 2 was found to display considerably stronger orientational correlations than N 2 . Structural differences between oxygen at 4.3 and 1.2 GPa can be explained by the different densities of these systems.

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Section: Introductionmentioning

confidence: 98%

Orientational correlations in high-pressure fluid oxygen and nitrogen

et al. 2008

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“…18 with experimental data from polarized neutron diffraction measurements. 12 Overall, the agreement between theory and experiment is fairly good. The dip at 2 Å −1 in the calculated I͑Q͒ reproduces the trend in the experimental data and the shoulder observed around 1 -1.5 Å −1 in the experiment corresponds well to the main peak in the calculated result.…”

Section: Magnetic Structure Factorsmentioning

confidence: 74%

“…and where U͑ , ͒ corresponds to the spin rotation matrix: We note that the matrix element 21 is given by the complex conjugate of 12 and that four real numbers are needed to represent the density matrix at a given point in real space. The present scheme does not impose any explicit condition on m͑r͒, improving on earlier methods, in which atomic spheres were used with a uniform direction of the magnetization in each sphere.…”

Section: ͑5͒mentioning

confidence: 99%

“…Using a spinpolarized neutron scattering technique, Deraman et al could separate out the magnetic component, revealing strong shortrange antiferromagnetic correlations. 12 In its ground state, the oxygen molecule is in a triplet spin state ͑ 3 ⌺ g − ͒, corresponding to two unpaired electrons, coupled ferromagnetically according to Hund's rule. Liquid oxygen shows paramagnetic properties, with a magnetic susceptibility closely obeying a Curie-Weiss law.…”

Section: Introductionmentioning

confidence: 99%

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Noncollinear magnetism in liquid oxygen: A first-principles molecular dynamics study

Oda

Pasquarello

2004

Phys. Rev. B

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We perform first-principles molecular dynamics of liquid oxygen in which the magnetic structure evolves according to a generalized density-functional scheme allowing for noncollinear spin configurations. We investigate both structural correlations between the orientations of the molecular axes and magnetic correlations between the orientations of the molecular magnetic moments, demonstrating a clear relation between the local molecular configuration and the relative magnetic arrangement. The nuclear structure factor obtained from the simulation is found to agree well with the experimental one. The calculated magnetic structure factor shows antiferromagnetic correlations between molecules in the first shell, in accord with spin-polarized neutron scattering measurements. We observe the formation of dynamically coupled molecules, known as O 4 units, in which the molecular moments are aligned in an antiferromagnetic fashion. An analysis based on the life time of such units, revealed that in most cases the O 4 units occur as transient configurations during collisions. However, we also observed a small fraction of O 4 units surviving for relatively long periods. To account for electronic excitations which are missed in our density-functional scheme, we complement our description with a mean field model for the thermal fluctuations of the magnetic structure. The combined scheme is found to improve the description of the magnetic neutron structure factor and allows us to study the dependence of the magnetic susceptibility on temperature.

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“…This local correlation has been pointed by G. N. Lewis, proposing the existence of nonmagnetic O 4 molecular unit to explain the smaller magnetic susceptibility [5]. After that, in spite of some neutron scattering experiments, the existence of O 4 has been controversial [6][7][8]. Alternatively, recent experimental and theoretical studies show that the antiferromagnetic O 2 -O 2 dimer state exists in liquid phase with sub ps lifetime [4,9].…”

Section: Introductionmentioning

confidence: 98%

Orbital Zeeman Effect of Liquid Oxygen in High Magnetic Fields

Nomura

Matsuda

Takeyama

et al. 2014

Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2013)

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Liquid oxygen is a magnetic fluid which shows anomalous properties due to the spin quantum number S = 1 of the molecular oxygen O 2 . Bimolecular absorption, which is the origin of the blue color in condensed oxygen, is a distinctive feature of the magnetic interaction. In this study, the magnetic field dependence of the bimolecular absorption is investigated. By applying the magnetic field, a deformation of the spectrum shape along with a reduction of the intensity is observed. The orbital Zeeman effect, which releases the degeneracy of the excited state, can explain the change of the spectrum width. To explain the smaller energy splitting comparing to the theoretical value, the effect of the randomly oriented molecules is taken into account. For a quantitative understanding of the orbital Zeeman effect of liquid oxygen, more detailed analyses will be required.

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A thermal neutron investigation of magnetic correlations in liquid oxygen

Cited by 22 publications

References 14 publications

Orientational correlations in high-pressure fluid oxygen and nitrogen

Orientational correlations in high-pressure fluid oxygen and nitrogen

Noncollinear magnetism in liquid oxygen: A first-principles molecular dynamics study

Orbital Zeeman Effect of Liquid Oxygen in High Magnetic Fields

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