The Experts below are selected from a list of 141 Experts worldwide ranked by ideXlab platform
Maria Gloria Pini - One of the best experts on this subject based on the ideXlab platform.
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Spin canting in a Dy-based single-chain magnet with dominant next-nearest-neighbor antiferromagnetic interactions
Physical Review B, 2009Co-Authors: Kevin Bernot, Javier Luzón, Andrea Caneschi, Dante Gatteschi, Roberta Sessoli, Lapo Bogani, Alessandro Vindigni, Angelo Rettori, Maria Gloria PiniAbstract:We investigate theoretically and experimentally the static magnetic properties of single crystals of the molecular-based Single-Chain Magnet (SCM) of formula [Dy(hfac)$_{3}$NIT(C$_{6}$H$_{4}$OPh)]$_{\infty}$ comprising alternating Dy$^{3+}$ and organic radicals. A peculiar inversion between maxima and minima in the angular dependence of the magnetic Molar Susceptibility $\chi_{M}$ occurs on increasing temperature. Using information regarding the monomeric building block as well as an {\it ab initio} estimation of the magnetic anisotropy of the Dy$^{3+}$ ion, this anisotropy-inversion phenomenon can be assigned to weak one-dimensional ferromagnetism along the chain axis. This indicates that antiferromagnetic next-nearest-neighbor interactions between Dy$^{3+}$ ions dominate, despite the large Dy-Dy separation, over the nearest-neighbor interactions between the radicals and the Dy$^{3+}$ ions. Measurements of the field dependence of the magnetization, both along and perpendicularly to the chain, and of the angular dependence of $\chi_{M}$ in a strong magnetic field confirm such an interpretation. Transfer matrix simulations of the experimental measurements are performed using a classical one-dimensional spin model with antiferromagnetic Heisenberg exchange interaction and non-collinear uniaxial single-ion anisotropies favoring a canted antiferromagnetic spin arrangement, with a net magnetic moment along the chain axis. The fine agreement obtained with experimental data provides estimates of the Hamiltonian parameters, essential for further study of the dynamics of rare-earths based molecular chains.Comment: 11 pages, 8 figure
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Spin canting in a Dy-based single-chain magnet with dominant next-nearest-neighbor antiferromagnetic interactions.
Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2009Co-Authors: Kevin Bernot, Javier Luzón, Andrea Caneschi, Roberta Sessoli, Lapo Bogani, Alessandro Vindigni, Angelo Rettori, A. Gatteschi, Maria Gloria PiniAbstract:We investigate theoretically and experimentally the static magnetic properties of single crystals of the molecular-based single-chain magnet of formula Dyhfac3NITC6H4OPh comprising alternating Dy3+ and organic radicals. The magnetic Molar Susceptibility M displays a strong angular variation for sample rotations around two directions perpendicular to the chain axis. A peculiar inversion between maxima and minima in the angular dependence of M occurs on increasing temperature. Using information regarding the monomeric building block as well as an ab initio estimation of the magnetic anisotropy of the Dy3+ ion, this “anisotropyinversion” phenomenon can be assigned to weak one-dimensional ferromagnetism along the chain axis. This indicates that antiferromagnetic next-nearest-neighbor interactions between Dy3+ ions dominate, despite the large Dy-Dy separation, over the nearest-neighbor interactions between the radicals and the Dy3+ ions. Measurements of the field dependence of the magnetization, both along and perpendicularly to the chain, and of the angular dependence of M in a strong magnetic field confirm such an interpretation. Transfer-matrix simulations of the experimental measurements are performed using a classical one-dimensional spin model with antiferromagnetic Heisenberg exchange interaction and noncollinear uniaxial single-ion anisotropies favoring a canted antiferromagnetic spin arrangement, with a net magnetic moment along the chain axis. The fine agreement obtained with experimental data provides estimates of the Hamiltonian parameters, essential for further study of the dynamics of rare-earth-based molecular chains.
Martin Jansen - One of the best experts on this subject based on the ideXlab platform.
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Synthesis, Structure, and Physical Properties of Cobalt Perovskites: Sr3CoSb2O9 and Sr2CoSbO6
Journal of Solid State Chemistry, 2001Co-Authors: Vicent Primo-martin, Martin JansenAbstract:The perovskites Sr3CoSb2O9, Sr2CoSbO6, and Sr2CoSbO5.63 have been synthesized in polycrystalline form by solid state reactions from acetate precursors as obtained by freeze-drying. The crystal structure of insulating Sr3CoSb2O9 has been refined from X-ray data by the Rietveld method and was found to be orthorhombic (Immm) with a=5.6411(1) Å, b=5.6610(1) Å, c=7.9829(2) Å. From the Molar Susceptibility curves an effective magnetic moment μeff=5.39μB and a spin-glass transition at ca. 6 K are deduced. The semiconducting perovskite Sr2CoSbO6 was synthesized by applying an elevated O2 pressure (3 kbar), and Co exclusively in the oxidation state +3 was attained. The Rietveld refinement of this compound has revealed a rhombohedral cell (R3m) with a=5.5992(2) Å and c=13.6609(2) Å and partial order (77%) of the B cations. An effective magnetic moment per formula unit of μeff=3.83μB and a spin-glass transition at ca. 47 K were observed. A semiconducting and oxygen-deficient perovskite, Sr2CoSbO5.63, was obtained by annealing Sr2CoSbO6 at 950°C in Ar. The Rietveld refinement proved it to be a double-cubic perovskite (Fm3m) with a=7.9658(1) Å, and a higher order of Co and Sb at the B sites (84%) was found, due to the formation of Co2+. From the magnetic Susceptibility data an effective moment of 4.85μB and a spin-glass transition at ca.17 K were deduced.
Nisha Choudhary - One of the best experts on this subject based on the ideXlab platform.
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Effect of substitution of magnetic rare earth Nd at non-magnetic La site on structure and properties of LaSrFeO4
Ceramics International, 2014Co-Authors: Devinder Singh, Suram Singh, Arun Mahajan, Nisha ChoudharyAbstract:Abstract K 2 NiF 4 phases La 1− x Nd x SrFeO 4 ( x =0.0, 0.3, 0.6, and 0.9) have been successfully prepared by solid-state reactions. Rietveld refinement shows that all the phases crystallize in tetragonal K 2 NiF 4 structure (space group I4 / mmm ). The change in the lattice constants was interpreted in terms of the ionic radius of the substituted ion. The variation of inverse Molar Susceptibility with temperature follows the Curie–Weiss law. The dominant magnetic interactions in the materials are antiferromagnetic, which could be due to Fe 3+ –O–Fe 3+ superexchange coupling. All the samples were semiconducting over the temperature range from 150 to 350 K and the resistivity data has been best fitted using the Arrhenius equation, ρ = ρ 0 exp(– E a / k B T ).
Kevin Bernot - One of the best experts on this subject based on the ideXlab platform.
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Spin canting in a Dy-based single-chain magnet with dominant next-nearest-neighbor antiferromagnetic interactions
Physical Review B, 2009Co-Authors: Kevin Bernot, Javier Luzón, Andrea Caneschi, Dante Gatteschi, Roberta Sessoli, Lapo Bogani, Alessandro Vindigni, Angelo Rettori, Maria Gloria PiniAbstract:We investigate theoretically and experimentally the static magnetic properties of single crystals of the molecular-based Single-Chain Magnet (SCM) of formula [Dy(hfac)$_{3}$NIT(C$_{6}$H$_{4}$OPh)]$_{\infty}$ comprising alternating Dy$^{3+}$ and organic radicals. A peculiar inversion between maxima and minima in the angular dependence of the magnetic Molar Susceptibility $\chi_{M}$ occurs on increasing temperature. Using information regarding the monomeric building block as well as an {\it ab initio} estimation of the magnetic anisotropy of the Dy$^{3+}$ ion, this anisotropy-inversion phenomenon can be assigned to weak one-dimensional ferromagnetism along the chain axis. This indicates that antiferromagnetic next-nearest-neighbor interactions between Dy$^{3+}$ ions dominate, despite the large Dy-Dy separation, over the nearest-neighbor interactions between the radicals and the Dy$^{3+}$ ions. Measurements of the field dependence of the magnetization, both along and perpendicularly to the chain, and of the angular dependence of $\chi_{M}$ in a strong magnetic field confirm such an interpretation. Transfer matrix simulations of the experimental measurements are performed using a classical one-dimensional spin model with antiferromagnetic Heisenberg exchange interaction and non-collinear uniaxial single-ion anisotropies favoring a canted antiferromagnetic spin arrangement, with a net magnetic moment along the chain axis. The fine agreement obtained with experimental data provides estimates of the Hamiltonian parameters, essential for further study of the dynamics of rare-earths based molecular chains.Comment: 11 pages, 8 figure
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Spin canting in a Dy-based single-chain magnet with dominant next-nearest-neighbor antiferromagnetic interactions.
Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2009Co-Authors: Kevin Bernot, Javier Luzón, Andrea Caneschi, Roberta Sessoli, Lapo Bogani, Alessandro Vindigni, Angelo Rettori, A. Gatteschi, Maria Gloria PiniAbstract:We investigate theoretically and experimentally the static magnetic properties of single crystals of the molecular-based single-chain magnet of formula Dyhfac3NITC6H4OPh comprising alternating Dy3+ and organic radicals. The magnetic Molar Susceptibility M displays a strong angular variation for sample rotations around two directions perpendicular to the chain axis. A peculiar inversion between maxima and minima in the angular dependence of M occurs on increasing temperature. Using information regarding the monomeric building block as well as an ab initio estimation of the magnetic anisotropy of the Dy3+ ion, this “anisotropyinversion” phenomenon can be assigned to weak one-dimensional ferromagnetism along the chain axis. This indicates that antiferromagnetic next-nearest-neighbor interactions between Dy3+ ions dominate, despite the large Dy-Dy separation, over the nearest-neighbor interactions between the radicals and the Dy3+ ions. Measurements of the field dependence of the magnetization, both along and perpendicularly to the chain, and of the angular dependence of M in a strong magnetic field confirm such an interpretation. Transfer-matrix simulations of the experimental measurements are performed using a classical one-dimensional spin model with antiferromagnetic Heisenberg exchange interaction and noncollinear uniaxial single-ion anisotropies favoring a canted antiferromagnetic spin arrangement, with a net magnetic moment along the chain axis. The fine agreement obtained with experimental data provides estimates of the Hamiltonian parameters, essential for further study of the dynamics of rare-earth-based molecular chains.
Vicent Primo-martin - One of the best experts on this subject based on the ideXlab platform.
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Synthesis, Structure, and Physical Properties of Cobalt Perovskites: Sr3CoSb2O9 and Sr2CoSbO6
Journal of Solid State Chemistry, 2001Co-Authors: Vicent Primo-martin, Martin JansenAbstract:The perovskites Sr3CoSb2O9, Sr2CoSbO6, and Sr2CoSbO5.63 have been synthesized in polycrystalline form by solid state reactions from acetate precursors as obtained by freeze-drying. The crystal structure of insulating Sr3CoSb2O9 has been refined from X-ray data by the Rietveld method and was found to be orthorhombic (Immm) with a=5.6411(1) Å, b=5.6610(1) Å, c=7.9829(2) Å. From the Molar Susceptibility curves an effective magnetic moment μeff=5.39μB and a spin-glass transition at ca. 6 K are deduced. The semiconducting perovskite Sr2CoSbO6 was synthesized by applying an elevated O2 pressure (3 kbar), and Co exclusively in the oxidation state +3 was attained. The Rietveld refinement of this compound has revealed a rhombohedral cell (R3m) with a=5.5992(2) Å and c=13.6609(2) Å and partial order (77%) of the B cations. An effective magnetic moment per formula unit of μeff=3.83μB and a spin-glass transition at ca. 47 K were observed. A semiconducting and oxygen-deficient perovskite, Sr2CoSbO5.63, was obtained by annealing Sr2CoSbO6 at 950°C in Ar. The Rietveld refinement proved it to be a double-cubic perovskite (Fm3m) with a=7.9658(1) Å, and a higher order of Co and Sb at the B sites (84%) was found, due to the formation of Co2+. From the magnetic Susceptibility data an effective moment of 4.85μB and a spin-glass transition at ca.17 K were deduced.