Effects of spin–orbit coupling and exchange in BaRuO<sub>3</sub>

Drillon, Marc; Padel, L.; Bernier, J.C.

doi:10.1039/f29797501193

Cited by 28 publications

(13 citation statements)

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“…The a 1 orbital will be half-filled, forming a Ru-Ru homopolar bond, which leaves a localized hole in the e Ϯ 3 manifold to give a large orbital angular momentum. A strong spin-orbit L⅐S coupling, which is commonly found in the 4d transition-metal compounds (32) This observation suggests that the unusual Ϫ1 (T) found for CaRuO 3 and its lack of long-range magnetic order is related to a spin-orbit coupling on the Ru 4ϩ ions that suppresses the ferromagnetic spin-spin coupling across the Ru-O-Ru bonds. Narrowing of the * band of SrRuO 3 by the introduction of the more acidic Ca 2ϩ ion and by reducing the Ru-O-Ru bond angle allows removal of the band degeneracy, which enhances the intraatomic spin-orbit coupling L⅐S to where it competes with the interatomic spinspin interaction across the Ru-O-Ru bonds having a bond angle much reduced from 180°.…”

Section: Resultsmentioning

confidence: 74%

High-pressure synthesis of the cubic perovskite BaRuO ₃ and evolution of ferromagnetism in ARuO ₃ (A = Ca, Sr, Ba) ruthenates

Chen

Zhou²,

Goodenough³

et al. 2008

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

183

160

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The cubic perovskite BaRuO3 has been synthesized under 18 GPa at 1,000°C. Rietveld refinement indicates that the new compound has a stretched Ru-O bond. The cubic perovskite BaRuO3 remains metallic to 4 K and exhibits a ferromagnetic transition at Tc ‫؍‬ 60 K, which is significantly lower than the Tc Ϸ 160 K for SrRuO3. The availability of cubic perovskite BaRuO3 not only makes it possible to map out the evolution of magnetism in the whole series of ARuO3 (A ‫؍‬ Ca, Sr, Ba) as a function of the ionic size of the A-site rA, but also completes the polytypes of BaRuO3. Extension of the plot of Tc versus rA in perovskites ARuO3 (A ‫؍‬ Ca, Sr, Ba) shows that Tc does not increase as the cubic structure is approached, but has a maximum for orthorhombic SrRuO3. Suppressing Tc by Ca and Ba doping in SrRuO3 is distinguished by sharply different magnetic susceptibilities (T) of the paramagnetic phase. This distinction has been interpreted in the context of a Griffiths' phase on the (Ca Sr)RuO3 side and bandwidth broadening on the (Sr,Ba)RuO3 side.magnetism ͉ compounds ͉ Ruthenate

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Section: Resultsmentioning

confidence: 74%

High-pressure synthesis of the cubic perovskite BaRuO ₃ and evolution of ferromagnetism in ARuO ₃ (A = Ca, Sr, Ba) ruthenates

Chen

Zhou²,

Goodenough³

et al. 2008

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

183

160

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“…Such calculations for ions in the orbitally degenerate 2 T 2g and 3 T 1g states are, for example, presented in Ref. 27. In particular, calculations performed within this formalism for Ru 4+ cluster with ruthenium ions in the low-spin configuration and induced by the spin-orbit coupling singlet ground state in BaRuO 3 perovskite demonstrate that the exchange interaction between Ru ions has to be taken into account to explain the temperature dependence of the magnetic susceptibility.…”

Section: Discussionmentioning

confidence: 99%

“…In particular, calculations performed within this formalism for Ru 4+ cluster with ruthenium ions in the low-spin configuration and induced by the spin-orbit coupling singlet ground state in BaRuO 3 perovskite demonstrate that the exchange interaction between Ru ions has to be taken into account to explain the temperature dependence of the magnetic susceptibility. 27 Taking all of that into account, it seems to justify the introduction of the molecular field acting on Ru spin in the discussion of the electronic structure of low-spin Ru 4+ ions which in the octahedral coordination are in 3 T 1g state. Then, if the molecular field is strong enough, a theory of the singlet ground state magnetism can be built up in the molecular field approximation.…”

Section: Discussionmentioning

confidence: 99%

Investigation of the magnetic properties ofY2Ru2O7byRu

et al. 2006

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Magnetic properties of the Mott insulator with the pyrochlore structure Y 2 Ru 2 O 7 were investigated using 99 Ru Mössbauer spectroscopy. Bulk magnetization measurements confirmed appearance of the spin-glass-like antiferromagnetic order with very large differences between zero-field-cooled and field-cooled magnetizations below the Néel temperature T N =76͑2͒ K. The Mössbauer spectra were obtained above and below T N . Analysis of the spectrum recorded at 4.2 K suggested a noncollinear local ordering of ruthenium magnetic moments. The electronic structure of the individual ruthenium ion, responsible for magnitudes of hyperfine parameters and the ruthenium magnetic moment, was discussed within the framework of the crystalline electric-field model, including the spin-orbit coupling and the exchange interaction in the molecular-field approximation. Reasonably good agreement between calculated and experimentally determined parameters was obtained. Simultaneously, the experimentally observed easy plane of ruthenium magnetic moments was explained. A. Sample preparation and characterizationPolycrystalline samples of Y 2 Ru 2 O 7 and Y 2 Ru 1.99 Sn 0.01 O 7 were prepared by the solid-state reaction from weighted in proper molar ratios mixtures of powders: Y 2 O 3 , RuO 2 , and enriched 119 SnO 2 . The mixtures were prereacted at 800°C for 12 h in air. After grinding they were pressed into pellets and sintered at 1150°C for 16 h in air. The grinding and sintering cycle was repeated several times. The x-ray-diffraction measurements were performed using Cu K␣ radiation in D501 Siemens powder diffractometer.

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“…5. An entire fit of ͑T͒ in the paramagnetic phase appears to require a Hamiltonian that includes exchange interactions and the spin-orbit coupling as put forward by Drillon et al 21 in interpreting ͑T͒ in the 9R phase of BaRuO 3 . Nevertheless, we have confirmed three important features in the magnetic susceptibility of Ca 3 Co 2 O 6 with strong spinorbit L · S coupling: ͑1͒ a eff significantly larger than the spin-only value, ͑2͒ a changing slope of −1 ͑T͒ that cannot be fit with a CW law, and ͑3͒ a highly anisotropic ͑T͒.…”

Section: A Thermal Conductivitymentioning

confidence: 99%

Thermal conductivity, electron transport, and magnetic properties of single-crystalCa3Co2O6

2009

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A recent neutron-diffraction study on the magnetic insulator Ca 3 Co 2 O 6 shows that spins in the c-axis chains of alternating Co1 octahedral and Co2 trigonal-prismatic face-sharing CoO 6/2 sites are ordered below T N with a long-wavelength modulation instead of a simple ferromagnetic chain as thought previously. Frustrated antiferromagnetic interchain interactions compete with ferromagnetic intrachain coupling to invalidate an Ising model despite a strong spin-orbit coupling L · S on the Co2 ions. We have carried out thermal conductivity, electron transport, and magnetic measurements on single-crystal Ca 3 Co 2 O 6 in order to characterize this complicated magnetic system. An anisotropic thermal-conductivity component superimposed at high temperatures on an isotropic phonon component is consistent with an exchange-interaction-mediated heat transfer. This observation is incompatible with an Ising model. The ferromagnetic intrachain interactions are argued to reflect a one-dimensional itinerant-electron band that is split by the c-axis translational symmetry and the on-site intra-atomic Hund exchange interaction with a localized S =3/ 2 spin on the Co2 ions.

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Effects of spin–orbit coupling and exchange in BaRuO₃

Cited by 28 publications

References 0 publications

High-pressure synthesis of the cubic perovskite BaRuO ₃ and evolution of ferromagnetism in ARuO ₃ (A = Ca, Sr, Ba) ruthenates

High-pressure synthesis of the cubic perovskite BaRuO ₃ and evolution of ferromagnetism in ARuO ₃ (A = Ca, Sr, Ba) ruthenates

Investigation of the magnetic properties ofY2Ru2O7byRu

Thermal conductivity, electron transport, and magnetic properties of single-crystalCa3Co2O6

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Effects of spin–orbit coupling and exchange in BaRuO3

Cited by 28 publications

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High-pressure synthesis of the cubic perovskite BaRuO 3 and evolution of ferromagnetism in ARuO 3 (A = Ca, Sr, Ba) ruthenates

High-pressure synthesis of the cubic perovskite BaRuO 3 and evolution of ferromagnetism in ARuO 3 (A = Ca, Sr, Ba) ruthenates

Investigation of the magnetic properties ofY2Ru2O7byRu

Thermal conductivity, electron transport, and magnetic properties of single-crystalCa3Co2O6

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Product

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About

Effects of spin–orbit coupling and exchange in BaRuO₃

High-pressure synthesis of the cubic perovskite BaRuO ₃ and evolution of ferromagnetism in ARuO ₃ (A = Ca, Sr, Ba) ruthenates

High-pressure synthesis of the cubic perovskite BaRuO ₃ and evolution of ferromagnetism in ARuO ₃ (A = Ca, Sr, Ba) ruthenates