FePt Texture Research Articles

Investigation on the microstructure and magnetic properties of FePt films prepared by sequentially sputtering

The FePt films were deposited with [Fe/Pt]n multilayer structure on preheated glass substrate by sequentially sputtering Fe and Pt layer in a magnetron sputtering system. The dependence of FePt's texture and magnetic properties on the multilayer structure was investigated. The XRD patterns indicate that FePt (111) texture are dominant for all [Fe/Pt]n multilayer films. However, the magnetic hysteresis (M-H) loops show that the samples with n=16 and 20 exhibit an obvious perpendicular anisotropy. The X-ray photoelectron spectroscopy (XPS) measurement results indicate that there are composition interfaces in the films. According to the micromagnetics simulation, it is concluded that the enhanced perpendicular magnetic anisotropy originates from the interface anisotropy, owing to the existence of the composition interfaces in the films.

Epitaxial Growth of L1$_{0}$–FePt Granular Thin Films on TiC/RuAl Underlayers

Highly ordered L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> FePt-oxide thin films with perpendicular texture and small grains were fabricated on a TiC underlayer along with a RuAl small grain size layer and a MgO seedlayer. The epitaxial growth from the MgO seedlayer to the TiC\RuAl grain size defining underlayer to FePt magnetic layer was studied. Perpendicular texture can be further improved by adjusting the thickness of each layer to optimize the in-plane stain. From our microstructure study, TiC/RuAl grain size defining layer was found effective in reducing the volume fraction of oxide in the film and the center-to-center grain size of FePt grains. With a thin Ag sacrificial layer inserted between TiC and FePt magnetic layer, a smaller grain size can be achieved, the ordering temperature was lowered, and the (001) texture of FePt was enhanced.

Highly Ordered FePt $L1_{0}$ Thin Films With Small Grains on RuAl Seed Layers

We present an experimental approach for obtaining highly ordered L10 FePt-oxide thin film media with small grains by using a RuAl layer as a grain size defining underlayer. In most previous studies, the FePt grain size was controlled by tuning the oxide volume fraction of the film. By introducing the RuAl grain size defining layer, 6 nm of FePt grains can be obtained at 520°C with 9% SiO2 in the film. A 5 nm thin barrier layer was introduced between FePt and RuAl to prevent the inter-diffusion between RuAl and FePt. The influence of different barrier layers was studied. With a thin Ag sacrificial layer inserted between the barrier layer and the FePt magnetic layer, a smaller grain size can be achieved, the ordering temperature was lowered, and the (001) texture of FePt was enhanced.

Effect of CrW underlayer on structural and magnetic properties of FePt thin films

L 1 0 ordered FePt thin films with face-centered-tetragonal (001) texture have been prepared by magnetron sputtering on Cr100−xWx underlayer. The dependence of Cr100−xWx microstructure and FePt texture on the W content in the Cr underlayer was investigated. The addition of W element in Cr underlayer enhances the Cr (200) texture and increases the lattice constant of Cr, which is favorable for lowering the transformation temperature from fcc to fct phase because of the increase of the tensile stress along the FePt a axis. A good FePt (001) texture is obtained on the Cr85W15 underlayer with a substrate temperature of 400°C. The coercivity of FePt thin films on CrW underlayer is higher than on Cr underlayer and increases with increasing W content in the Cr underlayer because the formation of the CrW alloy inhibits the diffusion between FePt and CrW layer. A 5nm Pt intermediate layer was employed to suppress the diffusion between FePt and CrW underlayer further.

(001) oriented FePt–Ag composite nanogranular films on amorphous substrate

By annealing the multilayer film with a stack structure of MgO 10 nm/Ag 20 nm/[FePt x nm/Ag 5 nm]5 at 550 °C for 1 h, (001)-oriented L10 FePt nanograins with high perpendicular magnetic anisotropy are obtained on an amorphous substrate. The 20-nm Ag underlayer plays an important role in improving (001) texture of FePt and decreasing the fct FePt ordering temperature. The switching volume and uniaxial magnetic anisotropy constant Ku of FePt–Ag composite films with a controllable FePt grain size are obtained by fitting the coercivity dependence on magnetic field sweeping rate employing coherent rotation model, taking into account the easy axis distribution.

Controlling the crystallographic orientation in ultrathin L1/sub 0/ FePt[111] films on MgO[111] underlayer

Controlling the crystallographic orientation in ultrathin FePt longitudinal media for ultrahigh recording density is discussed with introducing sputtered MgO[111] underlayers selected as a template for inducing [111] texture in the FePt films. The MgO[111] underlayers significantly enhanced the crystallographic texture of FePt[111] for films as thin as 10 nm or less. Full width at half maximum (FWHM) of FePt[111] reflection measured from XRD rocking curves and coercivity squareness (S*) confirmed the strong in-plane texture of the FePt films deposited on MgO(111) underlayers. FWHM and S* were 8/spl deg/ and 0.8, respectively. High coercivity of 3200 Oe could be achieved in films with very low M/sub r/t of 0.3 memu/cm/sup 2/ at moderate annealing temperature (/spl les/500/spl deg/C) which retained small grains.