Sputter-deposition of Co-Cr-Ta alloy layers on Ni-Zn ferrite plated underlayers

Abstract

Abstruct-The influence of Ni-Zn ferrite plated underlayers on grain size and magnetic characteristics of sputter-deposited Co-Cr-Ta layers was investigated. These properties were found to be strongly influenced by the surface texture of the underlayers. When the grain size of the underlayers was large (200-300 nm), the grains in the Co-Cr-Ta layers seemed to aggregate and were not isolated clearly. When the grain size of the underlayers was small (50-70 nm), the grain size in the Co-Cr-Ta layers decreased and the perpendicular coercivity increased to over 2 kOe. Further studies showed RE sputter-etching of the underlayers reduced grain size (30-50 nm), and increased perpendicular coercivity (3.0 kOe), presumably through a reduction of surface roughness and a formation of many fine nodules on the underlayers, which play a role of nucleation sites for the CO-Cr-Ta grains.

Microstructural, dielectric and magnetic behavior of spin-deposited nanocrystalline nickel–zinc ferrite thin films for microwave applications

“…Dielectric properties of the ferrite thin films at X-band microwave frequencies (8)(9)(10)(11)(12) were measured by using a Network Analyzer HP-8719ES, employing extended cavity perturbation method [27]. The cavity was made up of a standard X-band brass wave-guide of length 13.5 cm.…”

“…The real (A 0 ) and imaginary (A 00 ) parts of complex permittivity in X-band microwave frequency region (8)(9)(10)(11)(12) are shown in the Figs. 4(a) and (b) respectively.…”

“…In particular, nanocrystalline nickel-zinc ferrite thin films are of great interest at microwave frequencies not only due to properties like high resistivity (X10 6 O-cm) and lower losses but also because they can be easily prepared at lower annealing temperature [4][5][6][7][8][9][10]. Nickel-zinc ferrite thin films can also be used as non-reciprocal ferrite components on a microwave monolithic integrated circuit (MMIC) based on GaAs and as back layers to improve recording performances at high frequencies [11,12]. In an effort to fabricate nanocrystalline ferrite thin films compatible to planar microwave devices [13][14][15], thin films of nickel ferrite and zinc doped nickel ferrite with general composition Ni 1Àx Zn x Fe 2 O 4 (where x ¼ 0.0, 0.2 and 0.5) were grown by spin-deposition technique on various substrates such as ITO-coated 7059 glass, fused quartz and Si(1 0 0) at varying temperatures.…”

Synthesis of nanocrystalline nickel–zinc ferrite (Ni0.8Zn0.2Fe2O4) thin films by chemical bath deposition method

“…In particular, nanocrystalline nickel-zinc ferrite thin films are of great interest at microwave frequencies not only due to properties like high resistivity and lower losses but also because they can be easily prepared at lower annealing temperature [4][5][6][7][8][9][10]. Nickel-zinc ferrite thin films can also be used as non-reciprocal ferrite components on a microwave monolithic integrated circuit (MMIC) based on GaAs and as back layers to improve recording performances at high frequencies [11,12]. Ni-Zn ferrite is a type of mixed spinel in which tetrahedral (A) sites are occupied by Zn 2+ and Fe 3+ ions, whereas the octahedral (B) sites are occupied by Ni 2+ and Fe 3+ in the cubic spinel lattice.…”