Nickel clusters embedded in carbon nanotubes as high performance magnets

Abstract

Ensembles of fcc nickel nanowires have been synthesized with defined mean sizes in the interior of single-wall carbon nanotubes. The method allows the intrinsic nature of single-domain magnets to emerge with large coercivity as their size becomes as small as the exchange length of nickel. By means of X-ray magnetic circular dichroism we probe electronic interactions at nickel-carbon interfaces where nickel exhibit no hysteresis and size-dependent spin magnetic moment. A manifestation of the interacting two subsystems on a bulk scale is traced in the nanotube’s magnetoresistance as explained within the framework of weak localization.

Nickel nanoparticles inside carbon nanostructures: atomistic simulation

“…These graphene-metal hybrid structures are especially interesting because can display not only the individual properties of graphene but qualitatively new properties. Recently, nickel nanomagnets created in single-walled carbon nanotubes were obtained (Shiozawa et al 2015). Among other metals, nickel (especially nanocrystalline) plays an important role in fabrication of the composites being used in many industrial applications, for example, for aerospace and chemical industry, in nanoelectronics, chemical cells, to name a few.…”

Near-field infrared microscopy of nanometer-sized nickel clusters inside single-walled carbon nanotubes

“…This technique was already applied to investigate nanoparticles with magnetic behavior. [23][24][25] As the excellent magnetic properties of these nickel clusters were already demonstrated, 10 we expected to obtain the signal of nickel clusters in the MFM phase images as magnetic dipoles give bright and dark spots at their opposite poles. Fig.…”

“…Metallocenes in single-walled carbon nanotubes (SWCNTs) 7 represent a special class among these hybrid systems, as they constitute nanoreactors for both metal cluster formation 8 and inner nanotube growth. 9 In a recent study, 10 upon annealing nickelocene encapsulated in SWCNTs, superparamagnetic nickel clusters were formed that are considered as high performance single domain magnets with high coercivity. Here we measure such clusters by scattering-type near-eld optical microscopy (s-SNOM) to both probe the metallicity of such small nanostructures and to establish the sensitivity of the method.…”

“…Details of encapsulation of Ni(II) acetylacetonate in e-Dips single walled carbon nanotubes with tube diameters of 1.7 AE 0.1 nm are given in ref. 10. The encapsulated molecules were transformed to nickel clusters by annealing.…”

Exchange coupling in a frustrated trimetric molecular magnet reversed by a 1D nano-confinement

“…In the present work, we study the magnetic properties of Ni(acac) 2 -filled SWCNTs with mean diameters of 1. 2 inside SWCNTs has been confirmed by Raman spectroscopy according to the literature 10,[13][14][15][16][17][18][19] (see the ESI, section 2 † for more details). Fig.…”