Theoretical Study of Exchange Coupling in 3d-Gd Complexes: Large Magnetocaloric Effect Systems.
Polynuclear 3d transition metal-Gd complexes are good candidates to present large magnetocaloric effect. This effect is favored by the presence of weak ferromagnetic exchange interactions that have been investigated using methods based on Density Functional Theory. The first part of the study is dev...
| Publicado en: | Journal of the American Chemical Society Vol. 134; no. 25; pp. 10532 - 10543 |
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| Autores principales: | , , , , |
| Formato: | Artículo |
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American Chemical Society
6/27/2012
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| Materias: | |
| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=77605191&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 77605191 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 6/27/2012 vid: 134 iid: 25 pid: 997 pub: American Chemical Society artinfo: ui: 77605191 10.1021/ja302851n ppf: 10532 ppct: 11 formats: tig: atl: Theoretical Study of Exchange Coupling in 3d-Gd Complexes: Large Magnetocaloric Effect Systems. aug: au: Cremades, Eduard Gômez-Coca, Silvia Aravena, Daniel Alvarez, Santiago Eliseo Ruiz affil: Departament de Química Inorgànica and Institut de Recerca de Qulmica Teôrica i Computacional, Universitat de Barcelona, Diagonal 645, E-08028 Barcelona, Spain su: Magnetic properties of transition metal compounds Gadolinium compounds Ferromagnetism Density functionals Molecular orbitals Exchange reactions sug: subj: Magnetic properties of transition metal compounds Gadolinium compounds Ferromagnetism Density functionals Molecular orbitals Exchange reactions ab: Polynuclear 3d transition metal-Gd complexes are good candidates to present large magnetocaloric effect. This effect is favored by the presence of weak ferromagnetic exchange interactions that have been investigated using methods based on Density Functional Theory. The first part of the study is devoted to dinuclear complexes, focusing on the nature and mechanism of such exchange interactions. The presence of two bridging ligands is found more favorable for ferromagnetic coupling than a triple-bridged assembly, especially for complexes with small M-O...O-Gd hinge angles. Our results show the crucial role of the Gd Sd orbitals in the exchange interaction while the 6s orbital seems to have a negligible participation. The analysis of the atomic and orbital spin populations reveals that the presence of spin density in the Gd Sd orbital is mainly due to a spin polarization effect, while a delocalization mechanism from the 3d orbitals of the transition metal can be ruled out. We propose a numerical DFT approach using pseudopotentials to calculate the exchange coupling constants in four polynuclear first-row transition metal-Gd complexes. Despite the complexity, of the studied systems, the numerical approach gives coupling constants in excellent agreement with the available experimental data and, in conjunction with exact diagonalization methods (or Monte Carlo simulations), it makes it possible to obtain theoretical estimates of the entropy change due to the magnetization/demagnetization process of the molecule. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2012 holdings: @attributes: islocal: N |
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