title: Nonlinear and magneto-optical transmission studies on magnetic nanofluids of non-interacting metallic nickel nanoparticles.
abstract: Oxide free stable metallic nanofluids have the potential for various applications such as in thermal management and inkjet printing apart from being a candidate system for fundamental studies. A stable suspension of nickel nanoparticles of ∼ 5 nm size has been realized by a modified two-step synthesis route. Structural characterization by x-ray diffraction and transmission electron microscopy shows that the nanoparticles are metallic and are phase pure. The nanoparticles exhibited superparamagnetic properties. The magneto-optical transmission properties of the nickel nanofluid (Ni-F) were investigated by linear optical dichroism measurements. The magnetic field dependent light transmission studies exhibited a polarization dependent optical absorption, known as optical dichroism, indicating that the nanoparticles suspended in the fluid are non-interacting and superparamagnetic in nature. The nonlinear optical limiting properties of Ni-F under high input optical fluence were then analyzed by an open aperture z-scan technique. The Ni-F exhibits a saturable absorption at moderate laser intensities while effective two-photon absorption is evident at higher intensities. The Ni-F appears to be a unique material for various optical devices such as field modulated gratings and optical switches which can be controlled by an external magnetic field.
authors.affiliation: Department of Physics, Cochin University of Science and Technology, Cochin 682 022, India.
authors.forename: A P
authors.initials: AP
authors.lastname: Reena Mary
authors.forename: C S
authors.initials: CS
authors.lastname: Suchand Sandeep
authors.forename: T N
authors.initials: TN
authors.lastname: Narayanan
authors.forename: Reji
authors.initials: R
authors.lastname: Philip
authors.forename: Padraig
authors.initials: P
authors.lastname: Moloney
authors.forename: P M
authors.initials: PM
authors.lastname: Ajayan
authors.forename: M R
authors.initials: MR
authors.lastname: Anantharaman