Ex situ annealing method for c-axis oriented barium ferrite thick films

Abstract

A barium hexaferrite (BaFe12O19, magnetoplumbite structure, BaM) multilayered film, with a total thickness of 0.63 μm, was deposited on a Si substrate by stacking several 0.09 μm layers using a rf sputtering technique. Each 0.09 μm layer was ex situ annealed at 800 °C for 10 min prior to deposition of the succeeding layer. A vibrating sample/torque magnetometer was employed to characterize the magnetic properties of both the BaM multilayered and a single layered film of the same thickness. The 0.63 μm thick BaM multilayered and single layered films show a squareness (SQ=Mr/Ms at 7 kOe) of 0.81 and 0.62, respectively. An anisotropy field (HA) was found to be 17 kOe for the BaM multilayered film and 14.5 kOe for the single layered film. A stacking of BaM layers, with ex situ annealing between each layer, improves the c-axis orientation and anisotropy field as compared to a single layered film with the same thickness. This is attributed to limiting the number of nucleation sites for randomly oriented BaM crystallites existing in films thicker than 0.1 μm.

Magnetic properties of hexagonal strontium ferrite thick film synthesized by sol–gel processing using SrM nanoparticles

“…The S block contains two oxygen layers forming a spinel structure and R block is a three oxygen layer block, containing the strontium ion. Strontium hexaferrite thick film is an attractive candidate for MMIC applications, due to its ability to be self-biased by a high anisotropy field, large resistivity, high permeability, narrow magnetic anisotropy field distribution, and chemical stability [3][4][5].…”

Preparation and characterization of ZnSn-substituted barium ferrite thin films

“…As a result, none of the as-deposited films showed ferrimagnetic behavior, as was observed before for the basic BaFe 12 O 19 composition [3][4][5][6]8,9]. In fact, after the subtraction of the contribution of the sample holder and of the substrate, only a very weak diamagnetic component was observable.…”

“…The films did not crystallize even after annealing at 700 1C for 70 h. This clearly suggests that annealing above 700 1C is necessary for the crystallization of these BaZn x Sn x Fe 12 À 2x O 19 films. Indeed, most of the previous work [3][4][5][6]9] on the basic barium ferrite composition (BaFe 12 O 19 ) reported that 800 1C was required for the crystallization to take place. The nucleation of barium ferrite crystals was observed at 700-800 1C by Sui and Kryder [9], which is in agreement with this study and with [8].…”

“…The sputtering process has been applied previously for the preparation of BaFe 12 O 19 films [3][4][5][6][7][8][9], but there are very scarce data on the use of this technique for the preparation of the more complex barium ferrite systems [6], such as BaMe II…”

Magnetic properties of c-axis oriented Sr0.8La0.2Fe11.8Co0.2O19 ferrite film prepared by chemical solution deposition

“…For decades, M-type hexaferrites have attracted many attentions not only due to their high electromagnetic performance and excellent chemical stability of oxides at high temperature in air [1][2][3][4][5], but also due to high magnetocrystalline anisotropy, and high coercivity (H c ) in the form of thin film, which make them have potential applications in low-noise high-density digital recording media [6] and microwave devices due to high permittivity at high frequency [7]. In order to satisfy the requirements for high-density recording media, the films should behave high coercivity to record bits with narrow transition length and a moderate remnant magnetization (M r ) to achieve high signal to noise ratio [8].…”