Investigation of New Soft Magnetic Films for GHz Magnetic Recording Heads and Integrated Inductors

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Soft magnetic films with low coercivity and high permeability are critical building blocks in numerous electromagnetic devices such as magnetic recording heads, integrated inductors (microinductors), integrated transformers, magnetic sensors, and micromachined motors. However, a lack of soft magnetic materials with a high saturation magnetization (20 kG), a large permeability (1000), and a large ferromagnetic resonance frequency (1 GHz), tends to be the bottleneck in these applications. For example, the data rate of hard disk drives is expected to be ~1 Gb/s (1 Gb = 1 billion bits) by year 2003. A data rate of 2 Gb/s corresponds to a recording frequencies of ~1 GHz, which exceeds the ferromagnetic resonance (FMR) frequency of most magnetic materials. Therefore, it is increasingly urgent to investigate new materials, magnetization dynamics, and recording physics which will enable magnetic recording at a frequency of 1 GHz. In this project, we propose the following: 1) Investigate a new soft magnetic material, namely Fe-Co-N films (FeCoN) with a saturation magnetization of ~24 kG, which will enable higher areal recording densities in hard disk drives (100 Gb per square inch). 2) Study magnetization dynamics and magnetic recording at 1 GHz, an important milestone if reduced to practice. 3) Evaluate the viability of the new FeCoN material for integrated inductors, which are desired for emerging applications such as portable wireless communication devices. 4) Educate graduate students and undergraduates about information storage technology via doctoral thesis research, research experience for under graduate (REU), and classroom teaching.