High frequency energy dissipation characterization in magnetic head

Fall 2007

Nikhil Mallavarapu
Jim Bain
Project description

I will be working with Professor James Bain on a research project at the data storage systems center this semester. The project aims to better characterize the losses in magnetic heads. There has been work done which indicates that most of the energy dissipation is due to gyromagnetic damping. However, it is unclear as to whether there is any eddy current loss as a secondary effect. I have provided an outline of the steps involved that will lead us to understand this better: • First step will be to carry out two sets of impedance measurements with and without a dc field applied (saturated and unsaturated respectively), for the write head up to 9 GHz. • These measurements would then be plotted and a least square curve fit would be carried out ensure that these values agree with those obtained from a circuit model of the head. • This would then give us the impedance of the head as a function of frequency for saturated and unsaturated cases, which can then be used to find permeability as a function frequency. • By analyzing the phase of this function, we could arrive at a result that would more accurately explain this extra loss.

In order to keep track of my progress there will be a weekly meeting scheduled with Professor Bain where we will discuss the developments that I have made over the course of the week. Also, at the end of the semester I will produce a 10 to 20 page report and also give a 15 to 20 minute final presentation to Professor Bain and a few others who are interested in the project where I will summarize all the major problems and developments that I encountered over the course of the semester.

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