Strain Gradient Elasticity in SrTiO3Membranes: Bending versus Stretching

Varun Harbola*, Samuel Crossley, Seung Sae Hong, Di Lu, Yorick A. Birkhölzer, Yasuyuki Hikita, Harold Y. Hwang

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Young's modulus determines the mechanical loads required to elastically stretch a material and also the loads required to bend it, given that bending stretches one surface while compressing the opposite one. Flexoelectric materials have the additional property of becoming electrically polarized when bent. The associated energy cost can additionally contribute to elasticity via strain gradients, particularly at small length scales where they are geometrically enhanced. Here, we present nanomechanical measurements of freely suspended SrTiO3 crystalline membrane drumheads. We observe an unexpected nonmonotonic thickness dependence of Young's modulus upon small deflections. Furthermore, the modulus inferred from a predominantly bending deformation is three times larger than that of a predominantly stretching deformation for membranes thinner than 20 nm. In this regime we extract a strain gradient elastic coupling of â 2.2 μN, which could be used in new operational regimes of nanoelectro-mechanics.

Original languageEnglish
Pages (from-to)2470-2475
JournalNano letters
Volume21
Issue number6
DOIs
Publication statusPublished - 24 Mar 2021

Keywords

  • elasticity
  • flexoelectricity
  • perovskite thin films
  • strain gradient elasticity

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