Direct Determination of the Magnetic Structure of the Delta Phase of Oxygen

Goncharenko, I. N.; Makarova, O. L.; Ulivi, Lorenzo

doi:10.1103/physrevlett.93.055502

Cited by 62 publications

(49 citation statements)

References 21 publications

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“…Upon cooling at ambient pressure, oxygen is in turn solidified to the paramagnetic γ-phase, the magnetically disordered (short-range ordered) β-phase (3,4), and ultimately the antiferromagnetic α-phase (5). Upon compressing to approximately 6 GPa, the α-phase transforms into the antiferromagnetic δ-phase (6)(7)(8). Under a higher pressure of approximately 8 GPa, the magnetic order of oxygen is destroyed, which leads to the ε-O 8 phase consisting of O 8 clusters (9, 10).…”

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confidence: 99%

Spiral chain O ₄ form of dense oxygen

Zhu

Wang

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

111

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Oxygen is in many ways a unique element: It is the only known diatomic molecular magnet, and it exhibits an unusual O 8 cluster in its high-pressure solid phase. Pressure-induced molecular dissociation as one of the fundamental problems in physical sciences has been reported from theoretical or experimental studies of diatomic solids H 2 , N 2 , F 2 , Cl 2 , Br 2 , and I 2 but remains elusive for molecular oxygen. We report here the prediction of the dissociation of molecular oxygen into a polymeric spiral chain O 4 structure (space group I4 1 ∕acd, θ-O 4 ) above 1.92-TPa pressure using the particleswarm search method. The θ-O 4 phase has a similar structure as the high-pressure phase III of sulfur. The molecular bonding in the insulating ε-O 8 phase or the isostructural superconducting ζ-O 8 phase remains remarkably stable over a large pressure range of 0.008-1.92 TPa. The pressure-induced softening of a transverse acoustic phonon mode at the zone boundary V point of O 8 phase might be the ultimate driving force for the formation of θ-O 4 . Stabilization of θ-O 4 turns oxygen from a superconductor into an insulator by opening a wide band gap (approximately 5.9 eV) that originates from the sp 3 -like hybridized orbitals of oxygen and the localization of valence electrons.solid oxygen | spiral chain structure A s a long-standing problem in physics and chemistry, as well as earth and planetary sciences, high-pressure dissociation of diatomic molecules, such as H 2 , N 2 , O 2 , F 2 , Cl 2 , Br 2 , and I 2 , has attracted a lot of attention. Among these molecular systems, solid oxygen is a system of particular interest and exhibits many unusual physical properties by virtue of its molecular spin and the resultant spin-spin interactions, which make the system a critical test case for condensed-matter theory (1, 2). Oxygen is also the third most abundant element in the Solar System, and its behavior under extreme pressures provides important insight into the oxygen-related systems for a better understanding of the physics and chemistry of planetary interiors.Oxygen exhibits a rich polymorphism with seven unambiguously established crystalline phases. Upon cooling at ambient pressure, oxygen is in turn solidified to the paramagnetic γ-phase, the magnetically disordered (short-range ordered) β-phase (3, 4), and ultimately the antiferromagnetic α-phase (5). Upon compressing to approximately 6 GPa, the α-phase transforms into the antiferromagnetic δ-phase (6-8). Under a higher pressure of approximately 8 GPa, the magnetic order of oxygen is destroyed, which leads to the ε-O 8 phase consisting of O 8 clusters (9, 10). The ε-O 8 phase displays the bonding characteristics of a closedshell system, in which the intermolecular interactions primarily involve the half-filled 1π g Ã orbital of O 2 (11). Above 96 GPa, ε-O 8 has been observed to transform into a metallic ζ-phase (12, 13) and intriguingly exhibits superconductivity with a transition temperature of 0.6 K (14). This superconducting ζ-phase has been predicted by theory ...

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confidence: 99%

Spiral chain O ₄ form of dense oxygen

Zhu

Wang

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

111

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“…At present, six phases of solid oxygen having distinct crystallographic properties at different pressure and temperature (P -T ) [3,4] are established unambiguously. A seventh phase has been observed under high pressure but the magnetic interaction which is essential for the molecular arrangement is not well established [5].…”

Section: Introductionmentioning

confidence: 99%

“…As solid oxygen becomes denser, its volume practically decreases while its color becomes darker. Under very high pressure, solid oxygen which can be considered as "spin-controlled crystal" [2] changes its magnetic order [4] and becomes a metal and, at low temperature of 0.6 K, it transforms to a superconducting state, assigned by neutron-diffraction study [6]. The epsilon phase of solid oxygen (ε-O 2 ) is red in color.…”

Section: Introductionmentioning

confidence: 99%

First Principles Calculation of ε-Phase of Solid Oxygen

et al. 2016

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The electronic structures of ε-phase of solid oxygen (O2)4 are studied within the framework of densityfunctional theory. The intriguing molecule has been known to have magnetic properties at room temperature by applying pressure. Nevertheless, until now there was no evidence of band structure studied in the antiferromagnetic behaviour of (O2)4. We report a comparison study for spin and non-spin polarization orbital which suggests that this ferromagnetic configuration of (O2)4 could not be seen experimentally, and antiferromagnetic configuration of (O2)4 was seen at higher pressure of about 10 GPa. The antiferromagnetic state transforms into the superconducting state as the sample temperature decreases. The results can serve as a useful approximation in studying general features of the electronic structure. The (O2)4 clusters are reported in the Raman study, having significant absorption at 1516 cm −1 below infrared region.

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“…The techniques developed in the Laboratoire Léon Brillouin allowed us to combine very low temperatures (down to 0.1 K), magnetic fields (up to 8 Tesla) with singlecrystal and powder neutron diffraction [1]. The extended range of thermodynamical parameters revealed new phenomena in ''exotic'' magnetic material, such as molecular magnets (O 2 ) [2][3], topologically frustrated systems (Laves phases or pyrochlores) or systems close to the instability limit between the localized and itinerant magnetic states [4][5][6][7]. Pressure modifies magnetic interactions, changes the balance between different magnetic sublattices and can induce magnetic collapse when exceeds some critical value.…”

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confidence: 99%