Nanodomain formation on ferroelectrics and development of hard-disk-drive-type ferroelectric data storage devices

In this study, several read/write (R/W) tests were conducted using a hard-disk-drive-type ferroelectric data storage test system based on scanning nonlinear dielectric microscopy (SNDM). A periodically inverted signal, which corresponded to artificial domain stripes formed on LiTaO₃ single crystal, could be read correctly with a bit rate of 2 Mbps using this test system. Bit writing on a 50-nm-thick epitaxial LiTaO₃ film at 20Mbps was also demonstrated. In addition, a noncontact probe-height control technique was adapted to solve the problem of tip abrasion. The gap distance between a probe and a medium surface was successfully controlled on the nanometer order using a noncontact SNDM technique with sharp-pointed tungsten needle probes prepared by electrolytic polishing. Bit writing under a noncontact state was also studied. Artificial domain dots with diameters of less than 100nm could be formed under the noncontact state.