title: High coercive field and magnetization reversal in core-shell cum nanotwin driven Ni/NiO nanospheres.
abstract: We report here nanotwin-core-shell Ni(core)NiO(shell) spheres of average size 25 nm prepared through polyol method. They exhibit high coercive field at 2 K, sharp peak at approximately 20 K in magnetization curve and magnetization reversal. Interestingly, exchange bias due to antiferromagnetic NiO shell is absent. Among other possibilities, anisotropy variations due to particle size distribution and twinning associated with disorder appear to play an important role. Further, magnetic interactions of twinned bigger spheres, which may also act as superferrimagnetic-like Ni multilayer cores, with superparamagnetic Ni of smaller spheres, might be the additional causes. These nanostructures therefore seem to have potential interest in memory effect.
authors: UGC-DAE Consortium for Scientific Research, Indore 452001, MP, India.
authors: Gunadhor S
authors: GS
authors: Okram
authors: Ajay
authors: A
authors: Soni
authors: D T
authors: DT
authors: Adroja
authors: N P
authors: NP
authors: Lalla
authors: T
authors: T
authors: Shripathi
mesh_terms: D008280:Magnetics; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D009532:Nickel / Q000737:chemistry*
chemical_list: D009532:Nickel; C028007:nickel monoxide