IBM creates ‘world’s smallest’ magnetic computer memory bit

IBM claims to have created the world’s smallest magnetic computer memory bit using only 12 atoms.

The US computer company said the experimental low-temperature memory is at least 100 times denser than today’s hard-disk drives and solid-state memory chips, which use around one million atoms to store a single bit of information.

It hopes that the research, published today in the peer-reviewed journal Science, will provide the ability to build components an atom at a time and lead to smaller, faster and more energy-efficient devices.

‘The chip industry will continue its pursuit of incremental scaling in semiconductor technology but, as components continue to shrink, the march continues to the inevitable end point: the atom,’ said IBM Research lead investigator Andreas Heinrich.

‘We’re taking the opposite approach and starting with the smallest unit — single atoms — to build computing devices one atom at a time.’

The computer industry has been able to manufacture increasingly smaller microchips, following a pattern known as Moore’s law, for decades, but the physical limitations of traditional scaling techniques mean this cannot continue indefinitely.

IBM said that an alternative approach of building nanostructures one atom at a time and using an unconventional form of magnetism called anti-ferromagnetism allows computer memory to store 100 times more information in the same space.

Computers store information in tiny regions called ‘bits’ that are given values of either 1 or 0 according to the direction of an atomic property called magnetic spin.

The use of traditional ferromagnetism limits the size of computer memory, because if you place individual bits too close together the magnetic field from one can affect that of its neighbour.

The scientists at IBM Research used a scanning tunnelling microscope (STM) to atomically engineer a grouping of 12 coupled atoms that were anti-ferromagnetic, meaning their direction of magnetic spin alternated.

This meant they could pack adjacent magnetic bits much closer together than was previously possible, increasing the magnetic storage density without disrupting the state of neighbouring bits.