Electrical Engineering
      and Computer Sciences

Electrical Engineering and Computer Sciences


UC Berkeley


2010 Research Summary

Heat Assisted Magnetic Recording (HAMR)

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Eli Yablonovitch

California MICRO and California MICRO

Every electrical engineer is well aware of Moore's law; the exponential growth in the number of transistors the industry has been able to squeeze on a silicon die ever since Intel's 4004 microprocessor debuted in 1971 with 2300 of them. Few however are aware of the equally impressive exponential growth in the aerial density of magnetic storage media since IBM frist introduced the commercial hard disk drive in 1956. While the semiconductor industry is expected to run into trouble keeping up with Moore's law around 2030 as most device parameters will simultaneously reach fundamental physical limits, the magnetic storage industry is already in trouble as the magnetic domains used to store information on hard disks are becoming so small that they can barely maintain their magnetization in the face of random thermal energy fluctuations. To maintain the historical aerial density growth rate, sometime around 2012 the magnetic industry is expected to begin using a new recording technique known as heat assisted magnetic recording. This technique relies on the availability of near field transducers that can efficiently focus energy to the nanoscale. As the problem has been known for some time, several ideas have been put forth for such transducers, however none has come out ahead as a clearly superior device. As part of our work with the Western Digital head/media team we have surveyed the current art and then introduced lumped and distributed circuit element approaches to metal optics which we used to arrive at an optimal design for a new class of plasmonic near field transducers. Simulations show that our new class of transducers is theoretically able to achieve a level of energy focusing that far exceeds the projected requirements for the first generation of heat assisted magnetic recording drives. We are currently working closely with Western Digital to verify the efficacy of our near field transducers while keeping an eye out for other potentially promising solutions to the energy delivery problem.