title: Nanocolumnar interfaces and enhanced magnetic coercivity in preferentially oriented cobalt ferrite thin films grown using oblique-angle pulsed laser deposition.
abstract: Highly textured cobalt ferrite (CFO) thin films were grown on Si (100) substrates using oblique-angle pulsed laser deposition (α-PLD). X-ray diffraction and in-depth strain analysis showed that the obliquely deposited CFO films had both enhanced orientation in the (111) crystal direction as well as tunable compressive strains as a function of the film thicknesses, in contrast to the almost strain-free polycrystalline CFO films grown using normal-incidence PLD under the same conditions. Using in situ optical plume diagnostics the growth parameters in the α-PLD process were optimized to achieve smoother film surfaces with roughness values as low as 1-2 nm as compared to the typical values of 10-12 nm in the normal-incidence PLD grown films. Cross-sectional high resolution transmission electron microscope images revealed nanocolumnar growth of single-crystals of CFO along the (111) crystallographic plane at the film-substrate interface. Magnetic measurements showed larger coercive fields (∼10 times) with similar saturation magnetization in the α-PLD-grown CFO thin films as compared to those deposited using normal-incidence PLD. Such significantly enhanced magnetic coercivity observed in CFO thin films make them ideally suited for magnetic data storage applications. A growth mechanism based on the atomic shadowing effect and strain compression-relaxation mechanism was proposed for the obliquely grown CFO thin films.
authors.affiliation: Center for Integrated Functional Materials & Department of Physics, University of South Florida, Tampa, Florida 33620, United States. dmukherj@usf.edu
authors.forename: Devajyoti
authors.initials: D
authors.lastname: Mukherjee
authors.forename: Mahesh
authors.initials: M
authors.lastname: Hordagoda
authors.forename: Robert
authors.initials: R
authors.lastname: Hyde
authors.forename: Nicholas
authors.initials: N
authors.lastname: Bingham
authors.forename: Hariharan
authors.initials: H
authors.lastname: Srikanth
authors.forename: Sarath
authors.initials: S
authors.lastname: Witanachchi
authors.forename: Pritish
authors.initials: P
authors.lastname: Mukherjee