IBM has discovered how to store a bit of information in just 12 atoms, compared with the million or so normally required.
The technique, based on ferromagnetism, could in future allow smaller, faster and more energy-efficient devices to be built.
“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,” says Andreas Heinrich, lead investigator into atomic storage at IBM Research.
“We’re taking the opposite approach and starting with the smallest unit – single atoms – to build computing devices one atom at a time.”
Until now, it was unknown how many atoms it would take to build a reliable magnetic memory bit.
Ferromagnets use a magnetic interaction betweentheir constituent atoms that align all their spins – the origin of the atoms’ magnetism – in a single direction. While they’ve been used successfully for magnetic data storage in the past, miniaturizing this down to atomic dimensions hasn’t been possible because of the interaction of neighboring bits with each other.
The magnetization of one magnetic bit can strongly affect that of its neighbor as a result of its magnetic field. To harness magnetic bits at the atomic scale, it’s necessary to control the interactions between the bits.
The IBM Research team used a scanning tunneling microscope (STM) to atomically engineer a grouping of twelve antiferromagnetically coupled atoms that stored a bit of data for hours at low temperatures.
Taking advantage of their inherent alternating magnetic spin directions, they were able to pack adjacent magnetic bits much closer together than previously possible – greatly increasing the magnetic storage density without disrupting the state of neighboring bits.