Unusually large values of the E.P.R. spectra fine structure parameter of Cu(II) dimers with two-bridge exchange mechanisms

Воронкова, В. К.; Erëmin, M. V.; Mosina, L. V.; Yablokov, Yu. V.

doi:10.1080/00268978300102421

Cited by 17 publications

(5 citation statements)

References 7 publications

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“…The isotropic exchange interaction changes depending on the nature of the bridging it-electron systems, whereas the anisotropic effect is negligible and independent of the bridging systems. An unusual magnetism has been reported for binuclear Cu(II) complexes in which the isotropic exchange energy changes sharply, whereas the large anisotropic effect remains constant [15]. This peculiarity has been explained by a very simple model in accordance with the real changes of structure.…”

Section: Discussionmentioning

confidence: 60%

“…This peculiarity has been explained by a very simple model in accordance with the real changes of structure. The model includes as necessary elements the dependence of the properties on the geometry and electronic structure of the bridging group and the two-bridge exchange mechanisms [15]. In Cu2(bis-EDTAPDN) and Cu2(bis-EDTANAP), the antiferromagnetic interaction J is strong, although the two paramagnetic ions are separated by a number of diamagnetic atoms.…”

Section: Discussionmentioning

confidence: 99%

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Evaluation of exchange interaction in binuclear copper(II) chelates of amide-based cyclophanes

et al. 2001

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Temperature dependence of the electron paramagnetic resonance (EPR) spectra of binuclear Cu(II) complexes with amide-based cyclophanes, Cu 2 (bis-EDTAPDN), Cu2(bis-EDTANAP) and Cu2(bis-EDTABPE), in 60% methanol (pH ca. 10) has been studied at a frequency of 9.43 GHz in the temperature range of 77-4.2 K; the cyclophanes are macrocyclic compounds in which four amide bonds link two ethylenediaminetetraacetate (EDTA) units and two units of the aromatic diamine 1,4-phenylenediamine (DPN), 1,5-diaminonaphthalene (NAP) or bis(4-aminophenyl) ether (BPE). Exchange integrals found from the EPR measurements are ca. 70-105 cm -', 22 cm -' and J < 0, for Cu2(bis-EDTAPDN), Cu 2 (bis-EDTANAP) and Cu2(bis-EDTABPE), respectively; the sign of J is defined to be positive for antiferromagnetic interaction. The variation of exchange interactions in these compounds is related to the nature of the bridging organic groups.

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Section: Discussionmentioning

confidence: 60%

Section: Discussionmentioning

confidence: 99%

Evaluation of exchange interaction in binuclear copper(II) chelates of amide-based cyclophanes

et al. 2001

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“…[26,27], in such a geometry quantum interference between different exchange paths in the Cu-O plaquette strongly intensifies the ferromagnetic super-exchange coupling parameter J x 2 −y 2 ,xy with respect to the parameter J xy,xy for the ground state of the copper ions. This was experimentally confirmed by ESR measurements of metal-organic complexes [27], where an unusually large anisotropic exchange parameter J AE zz was found for Cu-Cu pairs connected via two bridging oxygen ligands. In the context of spin chains in copper oxides, such an effect was discussed in Ref.…”

Section: B Estimation Of the Anisotropic Exchange Parametersmentioning

confidence: 99%

“…In reference [27] the parameter J x 2 −y 2 ,xy was estimated as -330 cm −1 . If we assume that this value is relevant for the case of LiCuVO 4 too, then with g zz − 2 = 0.33 (see Ref.…”

Section: B Estimation Of the Anisotropic Exchange Parametersmentioning

confidence: 99%

Anisotropic exchange inLiCuVO4probed by ESR

et al. 2002

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We investigated the paramagnetic resonance in single crystals of LiCuVO 4 with special attention to the angular variation of the absorption spectrum. To explain the large resonance linewidth of the order of 1 kOe, we analyzed the anisotropic exchange interaction in the chains of edge-sharing CuO 6 octahedra, taking into account the ring-exchange geometry of the nearest-neighbor coupling via two symmetric rectangular Cu-O bonds. The exchange parameters, which can be estimated from theoretical considerations, nicely agree with the parameters obtained from the angular dependence of the linewidth.The anisotropy of this magnetic ring exchange is found to be much larger than it is usually expected from conventional estimations which neglect the bonding geometry. Hence, the data yield the evidence that in copper oxides with edge-sharing structures the role of the orbital degrees of freedom is strongly enhanced. These findings establish LiCuVO 4 as one-dimensional compound 1 at high temperatures.

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“…Exact calculations showed that this contribution is considerable and amounts e.g. for the Cu 2+ dimers [52] to J xy,x 2 −y 2 /k B ≈ −475 K. Note that this is one order of magnitude larger than the typical exchange constants between the groundstate orbitals as derived from the magnetic susceptibility in the above-mentioned spin-chain compounds. symmetries in the case of two bridging ligands following [29].…”

Section: Anisotropic Exchange Interactionsmentioning

confidence: 84%

Magnetic resonance in quantum spin chains with competing exchange interactions

Büttgen,

von Nidda

2024

J. Phys. A: Math. Theor.

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Based on a previous review on magnetic resonance in quantum spinchains [H.-A. Krug von Nidda, N. Büttgen, and A. Loidl, Eur. Phys. J. SpecialTopics 180, 161–189 (2010)] we report on further development in this field withspecial focus on transition–metal oxides and halogenides consisting of quasi one–dimensional spin systems, where both intra– and inter–chain exchange interaction may give rise to frustration effects and higher–order anisotropic exchange contributions like the Dzyaloshinskii–Moriya interaction become decisive for the formation of the magnetic ground state. Selected examples show how NMR and ESR contribute valuable information on the magnetic phases and exchange interactions involved:LiCuVO4 with competing nearest neighbour and next–nearest neighbour intra–chain exchange, LiCu2O2 with complex zig–zag chains, and Cs2CuCl4 where the chains form a triangular lattice with the inter–chain interaction weaker but of the same order of magnitude than the intra–chain interaction. The so called paper–chain compound Ba3Cu3In4O12, where each successive pair of CuO4 plaquettes is rotated by 90° with respect to its predecessor along the c–direction like in a paper–chain, provides an interesting topology of frustrated intra–chain exchange interactions. Finally, a few dimer systems are considered.

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Unusually large values of the E.P.R. spectra fine structure parameter of Cu(II) dimers with two-bridge exchange mechanisms

Cited by 17 publications

References 7 publications

Evaluation of exchange interaction in binuclear copper(II) chelates of amide-based cyclophanes

Evaluation of exchange interaction in binuclear copper(II) chelates of amide-based cyclophanes

Anisotropic exchange inLiCuVO4probed by ESR

Magnetic resonance in quantum spin chains with competing exchange interactions

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