The Crystallographic and Magnetic Properties of <i>Fe_3-xM_xO₄</i>(M=Ni, Zn) Magnetic Films prepared by Spin-Spray Ferrite Plating Method

Abstract

Abstract-In order to develop good backlayer for the Co-Cr perpendicular magnetic recording media, crystalline films of spinel, (Fe, Mi30AM=Ni and Zn) were prepared on glass substrates by spin-spray ferrite plating method. Reaction and oxidizing solution were sprayed in the reaction chamber in which the substrate is rotating. The reaction was influenced by concentration of reaction solution(R c ) and oxidizing solution(Oc), the flow rates of the reaction solution(R f ) and oxidizing so!ution(Oc), reaction temperature (T) and rotation speed of substrate(Sr). Under the condition where R r , OF60[rnQ/min], T=90(C] and Sr=150 [rpm], effect of Rc and Oc on the ferrite plating reaction were studied in aspect of chemical composition, crystallographic and magnetic properties. In the composition of Nio.34ZnO.6~e204' we have the stable crystaUographic and magnetic properties. I . INTRODUCTIONThere are several methods to perform ferrite plating to prepare the films with crystalline spinel structure in an aqueous solution at low temperature( < 90 "C) [1,2].Among them, "Spin-spray" method, in which a reaction solution and oxidizing solution are simultaneously sprayed onto a spinning substrate which is kept at 90 ["(:], is the most excellent technique for getting good quality films[3J.Ferrite films prepared in this method will be used of backlayer under Co-Cr films for inhabitation eddy current loss and improvement the high frequency properties of CoCr perpendicular magnetic recording media.Previously, the same process of the aspect using ferrite single-crystal substrate was studied, but we consider that using ferrite film is desirable from the practical view.In this paper, we report the crystallographic and magnetic properties of the Ni-Zn ferrite films which are deposited for spin-spray ferrite plating method. IT . EXPERIMENTAL METHODThe ferrite plating was performed by spin-spray method on glass substrates [4,5]. We used a reaction solution(pR=5.2) which contains FeCh4H 2 0, NiClz6H 2 0 and ZnCh and an oxidizing solution(pH=6.9) which contains NaN0 2 and CH 3 COONH 4 , simultaneously sprayed these two solutions for 30 min. The substrate was kept at 90rC] and spun at 150rpm during plating.We have performed magnetic properties(perpendicular to film plane) using VSM and crystalIographic properties using XRD. The surface and thickness in each layer were observed and measured by AFM and SEM, respectively. Also, the chemical composition of samples plated on the substrates were analyzed by ICP.