Research Paper

Journal of Nanoparticle Research

, Volume 13, Issue 1, pp 245-255

Morphology and magnetic properties of island-like Co and Ni films obtained by de-wetting

  • P. TibertoAffiliated withElectromagnetism Division, INRIM
  • , S. GuptaAffiliated withPolitecnico di Torino, DISMIC and DIFIS
  • , S. BiancoAffiliated withItalian Institute of Technology—IIT@POLITO, Center for Space Human Robotics
  • , F. CelegatoAffiliated withElectromagnetism Division, INRIM
  • , P. MartinoAffiliated withPolitecnico di Torino, DISMIC and DIFIS
  • , A. ChiolerioAffiliated withPolitecnico di Torino, DISMIC and DIFIS
  • , A. TagliaferroAffiliated withPolitecnico di Torino, DISMIC and DIFIS
  • , P. AlliaAffiliated withPolitecnico di Torino, DISMIC and DIFIS Email author 

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Abstract

The morphological, structural, and magnetic properties of Co and Ni films of different thicknesses grown by RF sputtering on a Si–SiO substrate and submitted to controlled diffusion of atoms on the substrate (de-wetting) are studied through X-ray diffraction (XRD), atomic force microscopy, X-ray photoelectron spectroscopy, and alternating-gradient magnetometry. For both metals, de-wetting treatment leads to the growth of non-percolating, metallic nanoislands characterized by a distribution of sizes and aspect ratios. XRD spectra reveal a polycrystalline multi-component structure evolving by effect of de-wetting and directly affecting the magnetic properties of films. The magnetic response after de-wetting is consistent with the formation of a nanogranular magnetic phase characterized by a complex, thickness-dependent magnetic behavior originating from the simultaneous presence of superparamagnetic and blocked-particle contributions. At intermediate film thickness (around 10 nm), a notable enhancement in magnetic coercivity is observed for both metals with respect to the values measured in precursor films and in their bulk counterparts.

Keywords

Magnetic nanoparticles Magnetic thin films De-wetting technique Coercive field