Researchers at the State University of New York at Buffalo have developed an extremely sensitive nanoscale device that could shrink ultra-high-density storage devices to incredibly small sizes.

The magnetic sensor, made of nickel and only a few atoms in diameter, could increase data storage capacity by a factor of a thousand or more and could ultimately lead to supercomputing devices as small as a wristwatch.

The effect created with the new nickel device is called ballistic magneto-resistance (BMR). It addresses a major hurdle facing advances in magnetic storage — that as stored bits of data get smaller, their magnetic field gets weaker, which makes the bits harder to read. Reliable reading of the data depends on producing a large enough magnetically-induced change in the electrical resistance of the sensor. The BMR experiment exhibited a record change in sensor resistance of more than 3,000 percent.

The ultimate capacity of the device is predicted to be about 1 terabit per square inch, which is 20 times higher than the most dense magnetic storage currently available. IBM's thermomechanical storage project, code-named Millipede, demonstrated a data storage density of 1 trillion bits per square inch earlier in June.

The current technology used in the sensors that read bits from a storage disk is based on an effect called giant magnetoresistance (GMR), which refers to the change in the sensor resistance when placed in a magnetic field. GMR sensors have enabled commercial hard drives that can store the amount of data contained in a full-length DVD movie in a space the size of a credit card. Sensors based on BMR, however, could enable the storage of 50 or more DVDs on a hard drive the size of a credit card.

BMR may also have applications beyond the data storage industry, such as improving magnetic measurements and the study of magnetic effects in individual atoms, molecules and nanoscale clusters. It could also greatly enhance resolution and sensitivity of scanning probe imaging techniques that are widely used to characterize magnetic materials.

The research, which was supported by the National Science Foundation, was carried out by Harsh Deep Chopra and Susan Hua and will be published in the July 1 issue of Physical Review B.