[Prof. Daesu Lee ] Flexoelectricity-Driven Mechanical Switching of Pol…

Caption: Flexoelectricity – driven mechanical polarization switching in CaTiO3 (111) thin film

(a) PFM phase change of CaTiO3 thin film by pressing AFM tip

(b) PFM phase image of ferroelectric domains generated by various AFM tip pressing force

(c) Stability of ferroelectric domains generated by AFM tip pressing

[Prof. Daesu Lee] Flexoelectricity-Driven Mechanical Switching of Polarization in Metastable Ferroelectrics

Flexoelectricity-based mechanical switching of ferroelectric polarization has recently emerged as a fascinating alternative to conventional polarization switching using electric fields. Here, we demonstrate hyperefficient mechanical switching of polarization exploiting metastable ferroelectricity that inherently holds a unique mechanical response. We theoretically predict that mechanical forces markedly reduce the coercivity of metastable ferroelectricity, thus greatly bolstering flexoelectricity-driven mechanical polarization switching. As predicted, we experimentally confirm the mechanical polarization switching via an unusually low mechanical force (100 nN) in metastable ferroelectric CaTiO3. Furthermore, the use of low mechanical forces narrows the width of mechanically writable nanodomains to sub-10 nm, suggesting an ultrahigh data storage density of ≥1 Tbit cm−2. This Letter sheds light on the mechanical switching of ferroelectric polarization as a viable key element for next-generation efficient nanoelectronics and nanoelectromechanics.

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