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Co-based amorphous alloys laminated with insulator for GHz frequency applications in magnetic write heads and other high frequency inductors, etc

IP.com Disclosure Number: IPCOM000019590D
Publication Date: 2003-Sep-22
Document File: 5 page(s) / 152K

Publishing Venue

The IP.com Prior Art Database


The laminate film with amorphous Co based Co-Zr-Ta (80-4-16 wt%) alloy film and alumna layer which was mechanically soft was incorporated into the write head, which recesses the laminate film from ABS. It was shown that the writer with the laminate yoke shows a single magnetic domain yoke, and shows significantly enhanced inductance bandwidth

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  Co-based amorphous alloys laminated with insulator for GHz frequency applications in magnetic write heads and other high frequency inductors, etc

  Reducing protrusion of the write head has been one of the key challenges for write head development with the areal density of the hard disk drives are approaching 100Gb/inch^2. Eddy current loss and hysteresis loss in write heads at high data rate writing processes contributes ~ 50% of the total protrusion, which is one of the key issues for writers. By laminating the metal magnetic materials with insulator layers and form the metal\insulate laminate during sputtering process, we can get achieve laminate films with excellent magnetic softness, reduce eddy current and hysteresis loss significantly, improve the roll-off frequency and enhance the high data rate performance.

To reduce eddy current and hysteresis loss in magnetic materials, we decide to choose the amorphous Co-based Co-Zr-Ta (80-4-16 wt%) alloy film. A brief comparison of properties of the CoZrTa film and the conventionally used NiFe alloys such as 80/20 and 45/55 is in Table 1 below. Clearly, The CoZrTa alloy has it advantage of high resistivity, extremely low magnetostriction constant, and coercivity.

Table 1: Magnetic properties of the CoZrTa alloy and the 80/20 and 45/55 NiFe alloys




Hk, Oe Ms, kG magnetostri Hc, Oection, ppm

 80/20 24 2.5 10 0.1 0.3 45/55 48 9.5 16 16 ~ 20 0.4 CoZrTa 100 16 ~ 18 12~13 -0.2 <0.1

In this disclosure, the [CoZrTa\Al2O3] laminate films with amorphous Co based Co-Zr-Ta (80-4-16 wt%) layer and alumina layer have been successfully applied to the pole materials for magnetic writer heads. The Co-based amorphous alloys have great soft magnetics. Figure 1 shows a typical hysteresis loop for a [CoZrTa 266nm\Al2O3 10nm]x6 laminate film with a total thickness of about 1.6 um, showing a straight line hysteresis loop in hard axis with an hard axis coercivity of 0.026 Oe and an anisotropy field of 18 Oe, the easy axis coercivity is 0.15 Oe.

The low coercivity [CoZrTa\Al2O3] laminate film is an excellent candidate for applications as pole material. However, the CoZrTa material is mechanical very soft. Figure 2 shows a nano-scratching test results of the different pole materials. The scratch profiles of the different alloys show the FeN alloys are harder than NiFe, while the NiFe and FeN alloy films are much harder than the CoZrTa films. This mechanical softness of the CoZrTa film is again confirmed in an AFM scan of the freshly cut surface of the CoZrTa film, as indicated in Fi...