SUNY Buffalo team eyes terabit hard drives

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Two professors at the State University of New York (SUNY) at Buffalo say they have come up with a way to put massive amounts of data onto smaller hard drives, using nanotechnology and magnetic fields to alter the path of electrons through a conductor.

Professors Harsh Deep Chopra and Susan Hua discovered a way to create an extremely responsive sensor by building what the researchers call a nanocontact, or an extremely small electrical conductor, in work completed last July. The pair recently found a way to more easily and reliably create the sensors, which could have enormous effects on the world of data storage.

The SUNY Buffalo researchers' sensor would allow hard drives to store data as densely packaged as a terabit (1 trillion bits) per square inch, Chopra said. Most standard PC hard drives can store anywhere from 20G bytes to 80G bytes, and are much larger than a square inch.

Electrons in conventional conductors of electricity move in a zig-zag pattern down the wire, Chopra said. The two researchers created a conductor that was so small -- anywhere from 1 nanometer (nm) to 10 nms long and wide -- it was less than the length of a single "zig," he said. One nanometer is equal to one billionth of a meter.

The small conductor forces the electron to move in a straight line, eliminating the zig-zag pattern, Chopra said. This is known as ballistic magnetoresistance.

When a magnetic field is applied to the small conductor as the electron travels through it, the researchers were able to measure levels of electrical resistance 3000 times higher than any level previously recorded, he said. Since those first results last July, the team has perfected its technique, resulting in resistance levels 33 times higher.

A standard hard drive uses read heads to store and access data. A magnetic field is applied to the data bits, and an electrified read head senses the amount of electrical resistance caused by the magnetic field to interpret the data. The data bits are about the same size as the read heads.

In order to use the new type of sensor in hard drives, manufacturers would place the nanocontacts close to magnetized bits of data, and measure the resistance caused by the magnetic field. Using the nanocontacts as read heads means that drive makers can use extremely small bits. The smaller the data bit on a hard drive, the stronger the sensor needs to be to measure those changes in resistance caused by the magnetic field.

The nanoscale sensors were made from nickel, with the nanocontact "whisker" sitting between two nickel electrodes, which produces the electrical current.

Applications for these sensors are still some time off, Chopra said. It usually takes about five to eight years for new hard-drive technology to make its way into products, he said. The researchers also need to better understand exactly what caused the enormous resistance change for the technology to be used reliably, he said.