Nanosized inverted domain dots in ferroelectric materials have potential application in ultrahigh density rewritable data storage systems. Herein, a data storage system is presented based on scanning non-linear dielectric microscopy and a thin film of ferroelectric single-crystal lithium tantalite. Through domain engineering, we succeeded in forming our smallest artificial nanodomain single dot at 5.1 nm diameter and an artificial nanodomain dot array with a memory density of 10.1 Tbit inch(-2) and a bit spacing of 8.0 nm, representing the highest memory density for rewritable data storage reported to date. Subnanosecond (500 ps) domain switching speed has also been achieved. Next, actual information storage with a low bit error and high memory density was performed. A bit error ratio of less than 1 × 10(-4) was achieved at an areal density of 258 Gbit inch(-2). Moreover, actual information storage is demonstrated at a density of 1 Tbit inch(-2).

An investigation of ultrahigh-density ferroelectric data storage based on scanning nonlinear dielectric microscopy (SNDM) is described. To obtain fundamental knowledge of high-density ferroelectric data storage, several studies of nanodomain formation in a congruent lithium tantalate single crystal were conducted. This paper is a summary report consisting of the most recent experimental data from investigations of ferroelectric high density data storage.

Unlike ideal 180°ferroelectric walls that are a unit cell wide ͑ϳ0.5 nm͒, real walls in ferroelectrics have been reported to be many nanometers wide ͑1-10 nm͒. Using scanning nonlinear dielectric microscopy of lithium niobate ͑LiNbO 3 ͒ and lithium tantalate ͑LiTaO 3 ͒ ferroelectrics, we show that the wall width at surfaces can vary considerably and even reach ϳ100 nm in places where polar defects adjoin a wall. The consequence of such variable wall widths is investigated on the specific property of threshold field required for wall motion. Using microscopic phase-field modeling, we show that the threshold field for moving an antiparallel ferroelectric domain wall dramatically drops by two to three orders of magnitude if the wall was diffuse by only ϳ1-2 nm, which agrees with experimental wall widths and threshold fields for these materials. Modeling also shows that wall broadening due to its intersection with a surface will influence the threshold field for wall motion only for very thin films ͑1-10 nm͒ where the surface broadening influences the bulk wall width. Such pre-existing and slightly diffuse domain walls with low threshold fields for wall motion may offer a general mechanism to explain significantly lower experimental coercive fields for domain reversal in ferroelectrics as compared to the thermodynamic predictions.

Nanosized inverted domain dots in ferroelectric materials have potential application in ultrahigh-density rewritable data storage systems. Herein, a data storage system is presented based on scanning nonlinear dielectric microscopy and a thin film of ferroelectric single-crystal lithium tantalite. Through domain engineering, nanosized inverted domain dots have been successfully formed at a data density above 10.1Tbit∕in.2 and subnanosecond (500ps) domain switching speed has been achieved. Moreover, actual information storage is demonstrated at a density of 1Tbit∕in.2

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