Nanometer-Scale Erasable Recording Using Atomic Force Microscope on Phase Change Media

We have demonstrated a nanometer-scale recording technique using an atomic force microscope (AFM) with an amorphous GeSb2Te4 film as a phase change medium. Data are recorded by changing the local electric properties of the film using a conductive AFM probe. The conductance of the film can be increased by more than one hundred times by applying a pulse voltage between the probe and the film. The recorded data are read by detecting the change in the conductance using the probe. The smallest possible recording region is 10 nm in diameter, which corresponds to a data storage density of 1 Tbit/cm2. The data can be erased by applying a negative DC voltage to the probe while scanning the probe over the film. The mechanisms of the reversible conductance change in the film are also discussed.