Flexoelectricity in Amorphous Hafnium Oxide (HfO2)

Flexoelectricity, inherent in all materials, offers a promising alternative to piezoelectricity for nanoscale actuation and sensing. However, its widespread application faces significant challenges: differentiating flexoelectric effects from those of piezoelectricity and other phenomena, verifying i...

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Bibliographic Details
Published in:arXiv.org 2024-09
Main Authors: Moreno-Garcia, Daniel, Howell, Kaitlin M, Villanueva, Luis Guillermo
Format: Article
Language:English
Subjects:
Actuation
Amorphous materials
Coefficients
Electrostriction
Hafnium oxide
Permittivity
Piezoelectricity
Thickness
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Summary:Flexoelectricity, inherent in all materials, offers a promising alternative to piezoelectricity for nanoscale actuation and sensing. However, its widespread application faces significant challenges: differentiating flexoelectric effects from those of piezoelectricity and other phenomena, verifying its universality across all material structures and thicknesses, and establishing a comprehensive database of flexoelectric coefficients across different materials. This work introduces a groundbreaking methodology that accurately isolates flexoelectricity from piezoelectric, electrostrictive and electrostatic effects, with a detection threshold extending below 1 fC/m. The robustness of this method is demonstrated through its application to amorphous hafnium oxide (HfO\(_2\)), successfully measuring a flexoelectric coefficient of 105 \(\pm\) 10 pC/m. This measurement signifies the first measurement of flexoelectricity in hafnia, as well as in any amorphous material. Additionally, the study compiles a list of published flexoelectric coefficients, revealing an important insight. The relationship between the flexoelectric coefficient and the material's relative permittivity is better approximated by a quadratic proportionality. This challenges the traditional linear assumption proposed in Kogan's work and opens new avenues for future research in flexoelectric materials.
ISSN:2331-8422