IBM said Thursday that it had learned how to better control magnetic fields at the atomic level, a technique that it could use in the future to help design next-generation storage elements.
In Science Express, Science magazine's online journal for time-sensitive papers, IBM researchers will detail how they aligned chains of up to 10 manganese atoms atop a thin insulator, measuring how the total magnetic properties changed as each atom was added.
"We have developed a window into the atomic heart of magnetism," said Andreas Heinrich, research staff member at IBM's Almaden Research Center in San Jose, California, in a statement. "We can now position atoms and then measure and control their magnetic interactions within precisely designed structures."
Magnetism derives from a property called "spin", which affects electrons and atoms. Although a spin can be either "up" or "down," the aggregate spin determines how magnetic a material is.
While most materials contain atoms whose "up" and "down" proportions are almost exactly the same, materials like iron usually favor one spin or the other, and are considered to be magnetically charged.
In 2004, IBM and Stanford formed a "spintronics" lab.
This charge becomes important for devices like hard drives, which use magnetic fields to store data.
Within the platter of a hard drive, magnetic grains are stored, that, depending upon their spin, signal the drive's head that they are either the "1" or the "0" of a data bit.
Cramming more bits into a disk platter increases its areal density, increasing the storage. Techniques like perpendicular recording manipulate this, to force the grain to align vertically and minimize the surface area of the grain.
If a grain becomes too small, however, its magnetic properties have a tendency to spontaneously flip, turning the data into random chaos. In 2004, IBM researchers learned exactly how much charge is needed to flip the spin of a single atom.
IBM's latest experiment helped determine how the spin of an atom or molecule is affected by adding more atoms to it, and thus how future storage devices can be constructed.
In all, IBM's test bed was just a 28-nanometer by 28-nanometer patch of copper and copper nitride. Each atom was "moved" into position through a scanning tunneling microscope, using magnetic fields 140,000 times stronger than the earth.
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