Molecule changes magnetism and conductance

One bit of digital information stored on a hard disk currently consists of about 3 million magnetic atoms. Researchers from Karlsruhe, Strasbourg, and Japan have now developed a magnetic memory with one bit per molecule.

By an electric pulse, the metal-organic molecule can be switched reliably between a conductive, magnetic state and a low-conductive, non-magnetic state.

''The superparamagnetic effect prevents smaller bit sizes from being reached in a hard disk,'' explains Toshio Miyamachi, first author of the study and researcher at the Center for Functional Nanostructures (CFN) of Karlsruhe Institute of Technology (KIT).

This super-paramagnetic effect implies that magnetic memory crystals are in-creasingly susceptible to thermal switching with decreasing size. Consequently, information may soon be lost.

''We chose another approach and placed a single magnetic iron atom in the center of an organic molecule consisting of 51 atoms. The organic shell protects the information stored in the central atom.''

Apart from the ultimate density of one bit per molecule, this type of memory based on so-called spin crossover molecules also has the advantage of the writ-ing process being reliable and purely electric.