The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
A. Shaulov - One of the best experts on this subject based on the ideXlab platform.
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Magnetic Relaxation in high temperature superconductors
Reviews of Modern Physics, 1996Co-Authors: Yehoshua Yeshurun, Ap Malozemoff, A. ShaulovAbstract:We review experimental studies of the time decay of the nonequilibrium magnetization in high-temperature superconductors, a phenomenon known as Magnetic Relaxation. This effect has its origin in motion of flux lines out of their pinning sites due to thermal activation or quantum tunneling. The combination of relatively weak flux pinning and high temperatures leads to rich properties that are unconventional in the context of low temperature superconductivity and that have been the subject to intense studies. The results are assessed from a purely experimental perspective and discussed in the context of present phenomenological theories. {copyright} {ital 1996 The American Physical Society.}
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Magnetic Relaxation in high-temperature superconductors
Reviews of Modern Physics, 1996Co-Authors: Yehoshua Yeshurun, Ap Malozemoff, A. ShaulovAbstract:We review experimental studies of the time decay of the nonequilibrium magnetization in high-temperature superconductors, a phenomenon known as Magnetic Relaxation. This effect has its origin in motion of flux lines out of their pinning sites due to thermal activation or quantum tunneling. The combination of relatively weak flux pinning and high temperatures leads to rich properties that are unconventional in the context of low temperature superconductivity and that have been the subject to intense studies. The results are assessed from a purely experimental perspective and discussed in the context of present phenomenological theories.
Wolfgang Wernsdorfer - One of the best experts on this subject based on the ideXlab platform.
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slow Magnetic Relaxation in a mononuclear eight coordinate cobalt ii complex
Journal of the American Chemical Society, 2014Co-Authors: Lei Chen, Jing Wang, Wolfgang Wernsdorfer, Xuetai Chen, Yiquan Zhang, You SongAbstract:The quest for the single-molecular magnets (SMMs) based on mononuclear transition-metal complexes is focused on the low-coordinate species. No transition-metal complex with a coordination number of eight has been shown to exhibit SMM properties. Here the Magnetic studies have been carried out for a mononuclear, eight-coordinate cobalt(II)-12-crown-4 (12C4) complex [CoII(12C4)2](I3)2(12C4) (1) with a large axial zero-field splitting. Magnetic measurements show field-induced, slow Magnetic Relaxation under an applied field of 500 Oe at low temperature. The Magnetic Relaxation time τ was fitted by the Arrhenius model to afford an energy barrier of Ueff = 17.0 cm–1 and a preexponential factor of τ0 = 1.5 × 10–6 s. The work here presents the first example of the eight-coordinate, mononuclear, 3d metal complex exhibiting the slow Magnetic Relaxation.
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Magnetic Relaxation pathways in lanthanide single molecule magnets
Nature Chemistry, 2013Co-Authors: Robin J Blagg, Wolfgang Wernsdorfer, Liviu Ungur, Floriana Tuna, James Speak, Priyanka Comar, David Collison, Eric J L Mcinnes, Liviu F Chibotaru, Richard E P WinpennyAbstract:Dysprosium alkoxides and dysprosium-doped yttrium alkoxides show very large energy barriers, greater than 800 K, to Magnetic Relaxation. These barriers arise from the presence of a strongly axial pseudo-octahedral crystal field, which switches off Relaxation through the first excited state that typically occurs in single-molecule magnets, and favours a competitive pathway through higher-energy states.
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multiple decker phthalocyaninato dinuclear lanthanoid iii single molecule magnets with dual Magnetic Relaxation processes
Dalton Transactions, 2012Co-Authors: Keiichi Katoh, Wolfgang Wernsdorfer, Yoji Horii, Nobuhiro Yasuda, Koshiro Toriumi, Brian K Breedlove, Masahiro YamashitaAbstract:The SMM behaviour of dinuclear Ln(III)–Pc multiple-decker complexes (Ln = Tb3+ and Dy3+) with energy barriers and slow-Relaxation behaviour were explained by using X-ray crystallography and static and dynamic susceptibility measurements. In particular, interactions among the 4f electrons of several dinuclear Ln(III)–Pc type SMMs have never been discussed on the basis of the crystal structure. For dinuclear Tb(III)–Pc complexes, a dual Magnetic Relaxation process was observed. The Relaxation processes are due to the anisotropic centres. Our results clearly show that the two Tb3+ ion sites are equivalent and are consistent with the crystal structure. On the other hand, the mononuclear Tb(III)–Pc complex exhibited only a single Magnetic Relaxation process. This is clear evidence that the Magnetic Relaxation mechanism depends heavily on the dipole–dipole (f–f) interactions between the Tb3+ ions in the dinuclear systems. Furthermore, the SMM behaviour of dinuclear Dy(III)–Pc type SMMs with smaller energy barriers compared with that of Tb(III)–Pc and slow-Relaxation behaviour was explained. Dinuclear Dy(III)–Pc SMMs exhibited single-component Magnetic Relaxation behaviour. The results indicate that the Magnetic Relaxation properties of dinuclear Ln(III)–Pc multiple-decker complexes are affected by the local molecular symmetry and are extremely sensitive to tiny distortions in the coordination geometry. In other words, the spatial arrangement of the Ln3+ ions (f–f interactions) in the crystal is important. Our work shows that the SMM properties can be fine-tuned by introducing weak intermolecular Magnetic interactions in a controlled SMM spatial arrangement.
Yehoshua Yeshurun - One of the best experts on this subject based on the ideXlab platform.
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Magnetic Relaxation in high temperature superconductors
Reviews of Modern Physics, 1996Co-Authors: Yehoshua Yeshurun, Ap Malozemoff, A. ShaulovAbstract:We review experimental studies of the time decay of the nonequilibrium magnetization in high-temperature superconductors, a phenomenon known as Magnetic Relaxation. This effect has its origin in motion of flux lines out of their pinning sites due to thermal activation or quantum tunneling. The combination of relatively weak flux pinning and high temperatures leads to rich properties that are unconventional in the context of low temperature superconductivity and that have been the subject to intense studies. The results are assessed from a purely experimental perspective and discussed in the context of present phenomenological theories. {copyright} {ital 1996 The American Physical Society.}
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Magnetic Relaxation in high-temperature superconductors
Reviews of Modern Physics, 1996Co-Authors: Yehoshua Yeshurun, Ap Malozemoff, A. ShaulovAbstract:We review experimental studies of the time decay of the nonequilibrium magnetization in high-temperature superconductors, a phenomenon known as Magnetic Relaxation. This effect has its origin in motion of flux lines out of their pinning sites due to thermal activation or quantum tunneling. The combination of relatively weak flux pinning and high temperatures leads to rich properties that are unconventional in the context of low temperature superconductivity and that have been the subject to intense studies. The results are assessed from a purely experimental perspective and discussed in the context of present phenomenological theories.
Danna E Freedman - One of the best experts on this subject based on the ideXlab platform.
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slow Magnetic Relaxation in a high spin iron ii complex
Journal of the American Chemical Society, 2010Co-Authors: Danna E Freedman, Hill W Harman, David T Harris, Gary J LongAbstract:Slow Magnetic Relaxation is observed for [(tpaMes)Fe]−, a trigonal pyramidal complex of high-spin iron(II), providing the first example of a mononuclear transition metal complex that behaves as a single-molecule magnet. Dc Magnetic susceptibility and magnetization measurements reveal a strong uniaxial Magnetic anisotropy (D = −39.6 cm−1) acting on the S = 2 ground state of the molecule. Ac Magnetic susceptibility measurements indicate the absence of slow Relaxation under zero applied dc field as a result of quantum tunneling of the magnetization. Application of a 1500 Oe dc field initiates slow Magnetic Relaxation, which follows a thermally activated tunneling mechanism at high temperature to give an effective spin-reversal barrier of Ueff = 42 cm−1 and follows a temperature-independent tunneling mechanism at low temperature. In addition, the Magnetic Relaxation time shows a pronounced dc-field dependence, with a maximum occurring at ∼1500 Oe.
You Song - One of the best experts on this subject based on the ideXlab platform.
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slow Magnetic Relaxation in a mononuclear eight coordinate cobalt ii complex
Journal of the American Chemical Society, 2014Co-Authors: Lei Chen, Jing Wang, Wolfgang Wernsdorfer, Xuetai Chen, Yiquan Zhang, You SongAbstract:The quest for the single-molecular magnets (SMMs) based on mononuclear transition-metal complexes is focused on the low-coordinate species. No transition-metal complex with a coordination number of eight has been shown to exhibit SMM properties. Here the Magnetic studies have been carried out for a mononuclear, eight-coordinate cobalt(II)-12-crown-4 (12C4) complex [CoII(12C4)2](I3)2(12C4) (1) with a large axial zero-field splitting. Magnetic measurements show field-induced, slow Magnetic Relaxation under an applied field of 500 Oe at low temperature. The Magnetic Relaxation time τ was fitted by the Arrhenius model to afford an energy barrier of Ueff = 17.0 cm–1 and a preexponential factor of τ0 = 1.5 × 10–6 s. The work here presents the first example of the eight-coordinate, mononuclear, 3d metal complex exhibiting the slow Magnetic Relaxation.
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a purely lanthanide based complex exhibiting ferroMagnetic coupling and slow Magnetic Relaxation behavior
Inorganic Chemistry, 2009Co-Authors: Zhi Chen, Bin Zhao, Peng Cheng, Xiaoqing Zhao, You SongAbstract:Two lanthanide−organic frameworks, {Ln(TDA)1.5(H2O)2}n [TDA = thiophene-2,5-dicarboxylic acid anion; Ln = Gd (1), Dy (2)], were structurally and Magnetically characterized. The Magnetic studies revealed that the ferroMagnetic coupling existed between adjacent lanthanide ions in 1 and 2, and only 2 displays slow Magnetic Relaxation behavior with τ0 = 2.4 × 10−8 s and ΔE/kB = 44.2 K. To our knowledge, it is rather rare that ferroMagnetic coupling and slow Magnetic Relaxation coexist in three-dimensional lanthanide-based frameworks.
