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Pàgina inicial > Articles > Articles publicats > Coupling of single, double, and triple-decker metal-phthalocyanine complexes to ferromagnetic and antiferromagnetic substrates |
Data: | 2014 |
Resum: | We report a survey of the magnetic properties of metal-organic complexes coupled to ferromagnetic and antiferromagnetic surfaces. Using element-resolved X-ray magnetic circular dichroism, we investigate the magnetism of single, double, and triple-decker phthalocyanines focusing on MnPc, TbPc, and TbPc deposited on Ni, Mn, and CoO thin films. Depending on the number of Pc ligands, we find that the metal ions within the molecules couple either parallel or antiparallel to a ferromagnetic substrate. Whereas single-decker complexes such as MnPc form a unique magnetic entity with ferromagnetic films, the intrinsic single molecule magnet properties of TbPc and TbPc remain largely unaltered. TbPc deposited on perpendicularly magnetized Ni films exhibits enhanced magnetic stability compared to TbPc in molecular crystals, opposite to TbPc deposited on in-plane magnetized Ni. Depending on the competition between uniaxial anisotropy, superexchange, and Zeeman interaction, the magnetic moment of TbPc can be aligned parallel or antiparallel to that of the substrate by modulating the intensity of an external magnetic field. This occurs also for TbPc, but the substrate-induced exchange coupling in triple-decker molecules is found to be short-ranged, that is, limited to the Tb ion closer to the ferromagnetic surface. Finally, we discuss the conditions required to establish exchange bias between molecules and antiferromagnetic substrates. We show that TbPc deposited on antiferromagnetic Mn thin films exhibits both exchange bias and enhanced coercivity when field cooled parallel to the out-of-plane easy axis. However, exchange bias does not extend to all molecules on the surface. On oxide antiferromagnets such as CoO we find no evidence of exchange bias for either TbPc or MnPc. |
Ajuts: | European Commission 203239 Ministerio de Ciencia e Innovación MAT2010-15659 Agència de Gestió d'Ajuts Universitaris i de Recerca 2009/SGR-695 |
Drets: | Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades. |
Llengua: | Anglès |
Document: | Article ; recerca ; Versió sotmesa a revisió |
Matèria: | Phthalocyanines ; Exchange bias ; Hybrid metal-organic interfaces ; XMCD |
Publicat a: | Surface Science, Vol. 630 (Dec. 2014) , p. 361-374, ISSN 0039-6028 |
Preprint 18 p, 6.5 MB |