Professor pushes hard disk limits

Vijay Jayaram Nov 7, 2011

Jimmy Zhu, an electrical and computer engineering professor, an Institute of Electrical and Electronics Engineers (IEEE) distinguished lecturer, and the holder of 12 U.S. patents, is currently the director of the Data Storage Systems Center (DSSC) here at Carnegie Mellon. Despite many contributions to his field of research, many CIT first-years know Zhu simply as an Introduction to Electrical Engineering recitation instructor. In an interview with The Tartan this past week, he shared details of his groundbreaking research, his current work, and some humorous anecdotes about grad school.

Zhu considers his work in the field of magnetic data storage — namely in hard disk drives (HDDs) — as his greatest research accomplishment. “When I was a graduate student in the mid-’80s,” he said, “the HDD could store only 10 megabytes, and people thought ... that was it!” To increase drives’ capacity, Zhu began work on the nanometer-scale microstructure of the metallic coating of the drive. This 10-nanometer-thick metal is filled with polar particles. When the transducer, which floats very slightly above the disk, applies a magnetic field, the particles line up in a certain way, some producing magnetic flux, others not. These physical states are analogous to ones and zeros, allowing data to be stored.

The process of keeping the transducer floating precisely over the disk, polarizing only the right particles, is immensely difficult, Zhu said. “In terms of scale,” he said, “it’s like keeping the Sears Tower hovering sideways a millimeter off the ground ... without consuming much power.” Ultimately, he developed this technology and revolutionized the field; in fact, Zhu’s method of magnetic data storage is still in use in the hard disk today, allowing drives to store terabytes of information.

Zhu is currently working with magnetoresisitive random access memory (MRAM). As the name suggests, this technology stores memory in magnetic states, which gives it three advantages over conventional static RAM and dynamic RAM. First, MRAM requires 10 times less power. Second, since it retains information even when the computer is powered off, booting up with MRAM is instantaneous. Last, it is far more secure than conventional RAM in outer space, where cosmic rays can disrupt data.

While he is heavily involved with research, Zhu shared some of his more light-hearted pursuits as well. He reminisced about his time at the University of California, San Diego, and how he often gathered his fellow researchers for a game of basketball to escape the monotony of the lab. He also enjoys traveling, both for work and to meet up with acquaintances around the world. “I’ve graduated 35 Ph.D. students, and I’m often invited to dinner with them when I visit the area,” he said.

When asked about his long list of achievements, Zhu said that he owes a lot to his physics and engineering backgrounds: “From my graduate school days, I’ve had the mind of an experimentalist. As an engineer, I can apply the results of these experiments to the real world.”

Over time, he said, he has developed his own personal philosophy, one that can apply to researchers in all disciplines. “When it comes down to research, I know I’ve got to make a measurable impact.... That’s my criterion for success.”