On Ti Underlayer <sub> 0 </ Sub> Texture Formation Of The Fept Nanoparticle Film L1

This paper has summarized the experimental and theoretical research progress of granular films firstly. And the present major problems to be solved have been discussed subsequently. The purpose and meaning of this paper are stated on this foundation. Soon afterwards this paper has introduced our work.In our experiments, FePt/Ti and FePt/(FePt)_xTi_1-x granular films were fabricated onto glass substrates using a dc facing-target magnetron sputtering system. Subsequently, the samples were in situ annealed at appropriate temperatures. The microstructures were examined by X-ray diffraction (XRD). Magnetic properties were measured by vibrating sample magnetometer (VSM). And the morphologies and domain structures were observed by scanning probe microscope (SPM). The microstructure and magnetic properties were analyzed as functions of the thickness of Ti layer (t), annealing temperature(T_a)and substrate temperature (T_s) in detail. The internal mechanism of Ti layer inducing FePt Ll₀ structure was summarized definitely.The thicknesses of Ti underlayer, annealing temperature and the orientation of the underlayer have great effects on the microstructure and magnetic properties of FePt films.With the addition of Ti, FePt(10 nm)/Ti(t nm) films possessed partly ordered Ll₀ (111) texture and the dispersion of grains is much more uniform than FePt monolayer films. When the thickness of Ti layer is beyond 2.5 nm, the surface average roughness begins to increase. The grains of films gather together slightly when annealing temperature is beyond 450℃. FePt/Ti film with most ordered Ll₀ structure is obtained at t = 2.5 nm and T_a = 550 ℃, which has maximum coercivity.SM curves show that the exchange-interaction between magnetic grains decreases significantly with the addition of thin Ti underlayer.Partly ordered Ti_x(FePt)_1-x (x vol.%) underlayer can induce epitaxial growth of the perfectly ordered Ll₀ structure FePt films. Mostly ordered Ll₀ texture in FePt(30 nm)/ Ti₇₈(FePt)₂₂ (45 nm) films is obtained at T_s = 250℃ and the average grain size is smaller than the films deposited at room temperature. Well-isolated domains were found in this sample and most of the grains exhibit single-domain structure.