Polarization Switching In Nanomagnets Could Lead To Better Storage Drives


University of Berkeley, California researchers have uncovered a way to switch nanomagnet polarization to pave the way for high-density storage solutions moving onto integrated circuits and away from hard disks.

In a study published in the journal Proceedings of the National Academy of Sciences, researchers led by Sayeef Salahuddin detailed their discovery that could potentially lead to turning computers on in an instant and using them at greater speeds while using significantly less power. According to them, tilting magnets at even the slightest angles can make them easily switchable without the need for an external magnetic field.

Salahuddin explained that reducing power requirements and increasing speed requires manufacturing a computer chip with a memory to come as close as possible to standard computational action. However, the physics of creating long-term storage are incompatible with integrated circuits. Building and switching magnetic polarity without external magnetic fields has been the aim of spintropics. Unfortunately, generating magnetic fields requires space and power, which is why magnets cannot be integrated onto today's computer chips.

Instead, long-term magnetic memory uses separate systems, including a hard disk where data is saved and random-access memory on integrated circuits fitted into the central processing unit. A significant amount of energy used by a computer is spent on transferring data from one memory type to another. And when the process speeds up, more heat is generated.

Salahuddin and colleagues have discovered in previous research that directing electrical currents across tantalum, a rare metal, results in magnetic polarity even when external magnetic fields are not over. This is a breakthrough but the researchers have another problem: vertically packing together nanomagnets results in an alignment that negates tantalum's switching effects.

"We found that by tilting the magnet - just 2 degrees was enough - you get all the benefits of a high-density magnetic switch without the need for an external magnetic field," said Salahuddin.

The study received support from the National Science Foundation Center for Energy Efficient Electronics Science, the Department of Energy and the Function Accelerated nanoMaterial Engineering Center of the Semiconductor Technology Advanced Research Network. Other authors include: Jeffrey Bokor, Jeongmin Hong, Dominic Labanowski, Debanjan Bhowmik, OukJae Jee and Long You.

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