IBM develops world’s smallest magnetic memory bit using only 12 atoms

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A team from IBM Research has created the world's smallest magnetic memory bit using only 12 atoms. This is significantly less than today's disk drives which use about 1million atoms to store a single bit of information.

The ability to manipulate matter atom by atom could pave the way for smaller, faster and more energy efficient devices. By working at an atomic level, the scientists were able to demonstrate magnetic storage that is at least 100times denser than modern disk drives and solid state memory chips. According to the team, future applications of nanostructures built one atom at a time, and that apply an unconventional form of magnetism called antiferromagnetism, could allow users to store 100 times more information in the same space. Andreas Heinrich, lead investigator into atomic storage at IBM Research, Almaden in California based the research on the fact that the most basic piece of information that a computer understands is a bit. Much like a light that can be switched on or off, a bit can have only one of two values: 1 or 0. Until now, it was unknown how many atoms it would take to build a reliable magnetic memory bit. With properties similar to those of magnets on a refrigerator, ferromagnets use a magnetic interaction between its constituent atoms that align all their spins – the origin of the atoms' magnetism – in a single direction. Ferromagnets have worked well for magnetic data storage but a major obstacle for miniaturising this down to atomic dimensions is the interaction of neighbouring bits with each other. The magnetisation of one magnetic bit can strongly affect that of its neighbour as a result of its magnetic field. Harnessing magnetic bits at the atomic scale to hold information or perform useful computing operations requires precise control of the interactions between the bits. The scientists at IBM Research used a scanning tunneling microscope (STM) to atomically engineer a grouping of 12 antiferromagnetically coupled atoms that stored a bit of data for hours at low temperatures. Taking advantage of their inherent alternating magnetic spin directions, they demonstrated the ability to pack adjacent magnetic bits much closer together than was previously possible. This greatly increased the magnetic storage density without disrupting the state of neighbouring bits. Heinrich said: "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. We're taking the opposite approach and starting with the smallest unit - single atoms - to build computing devices one atom at a time." The research is published in Science journal.