Modifying the interfacial conditions of magnetic layers by capping with overlayers can efficiently enhance the magnetic functionality of a material. However, the mechanisms responsible for this are closely related to the crystalline structure, compositional combinations, and interfacial quality, and are generally complex. In this contribution, we explored the use of Ag ultrathin overlayers on annealed . A method for preparing magnetic layers with different levels of enhanced magnetic anisotropy energy was developed. The method essentially involves simply modifying the contact area of the metallic/magnetic interface. A rougher interface results in a larger contact area between the Ag and Ni layers, resulting in an increase in magnetic anisotropy energy. Moreover, post-annealing treatments led to the segregation of Ni atoms, thus making the enhancement in the coercive force even more efficient. A model permits an understanding of the contact area and a strategy for enhancing the magnetic anisotropy energy and the coercive force was developed. Our approaches and the developed model promise to be helpful in terms of developing potential applications of ultrathin magnetic layers in the area of spintronics.
KEYWORDSbis(2,2-bipyridine)-5-amino-1,10-phenanthroline ruthenium(II), carbon nanotube, diazotization, photoinduced charge transfer, photomagnetism ABSTRACT Bis(2,2-bipyridine)-5-amino-1,10-phenanthroline ruthenium(II) (Ru(bpy) 2 (phen-NH 2 ) 2+ ), an MLCT complex, has a long-lived triplet state in water (λ ex :473 nm; λ em : 620 nm; τ = 615 ns; Φ = 1 relative to that of Ru(bpy) 3 2+ ) and a structure analogous to Ru(bpy) 3 2+ . When Ru(bpy) 2 (phen-NH 2 ) 2+ was subjected to diazotization in the presence of carbon nanotubes (CNTs), it formed nanodots on the CNTs, rendering the resulting tubes (Ru@CNT) capable of transducing photo stimuli (473 nm) into electricity and magnetism at ambient conditions. The increased functionality was highly reproducible, as evidenced by conductive-mode AFM, vibrating sample magnetometry (VSM), and AC susceptibility analysis. The local magnetism probing of the Ru@CNT with magnetic-mode AFM techniques (MFM) indicated that the magnetism originated from the unpaired electrons formed on the photoexcited nanodots. The resulting phase shift behaved as a function of the luminous power and the voltage (V b ) of the electrical bias applied to the Ru@CNT. The V b dependence deviated from the expected quadratic correlation, confirming that the formation of the photoinduced charge separation state at the nanodots is responsible for the photomagnetism. The Ru@CNT tubes showed mobility toward external magnets (65 Gauss) when floating on water and under 473-nm illumination.The Ru@CNT thus appears to be a multifunctional material that might be useful in spintronics.
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