An Ultraclean Tip-Wear Reduction Scheme for Ultrahigh Density Scanning Probe-Based Data Storage

Probe-based memory devices using ferroelectric media have the potential to achieve ultrahigh data-storage densities under high write−read speeds. However, the high-speed scanning operations over a device lifetime of 5−10 years, which corresponds to a probe tip sliding distance of 5−10 km, can cause the probe tip to mechanically wear, critically affecting its write−read resolution. Here, we show that the long distance tip-wear endurance issue can be resolved by introducing a thin water layer at the tip−media interfacethin enough to form a liquid crystal. By modulating the force at the tip−surface contact, this water crystal layer can act as a viscoelastic material which reduces the stress level on atomic bonds taking part in the wear process. Under our optimized environment, a platinum−iridium probe tip can retain its write−read resolution over 5 km of sliding at a 5 mm/s velocity on a smooth ferroelectric film. We also demonstrate a 3.6 Tbit/inch2 storage density over a 1 × 1 μm2 area, which is the highest density ever written on ferroelectric films over such a large area.