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Cracking Flexoelectricity
Gustau Catalan1, 2*, A. Abdollahi2,3, K. Cordero2, M. Arroyo3, I. Arias3
ICREA-Institucio Catalana de Recerca I Estudis Avançats, Barcelona, Spain
2
ICN2-Institut Catala de Nanociencia i Nanotecnologia (Severo Ochoa Excellence Centre), Campus UAB,
Bellaterra 08193, Barcelona, Spain
3
LaCaN-Laboratori de Càlcul Numèric, Departament d’Enginyeria, Universitat Politècnica de Catalunya
(UPC), Barcelona, spain
1
*e-mail: [email protected]
The recent surge of research on flexoelectricity (polarization induced by strain gradients)
has been fuelled by the realization that strain gradients scale in inverse proportion to size,
leading to magnified flexoelectric effects at the nanoscale1,2,3. By contrast,
piezoelectricity (polarization induced by strain) is a relatively size-independent property
and, as a consequence, there exists a range of sizes where flexoelectricity and
piezoelectricity are are of comparable magnitude and may cooperate or compete with
each other. The interaction between piezoelectricity and flexoelectricity leads to new
physical phenomena, not only in nanoscopic samples, but even in bulk single crystals
provided that these have nanoscopic features. Here I will discuss some of the effects that
emerge from the interplay between piezoelectricity and flexoelectricity, with emphasis on
new phenomena and in particular the discovery of broken inversion symmetry in
mechanical properties such as fracture toughness and crack propagation4.
1
Catalan et al, Flexoelectric rotation of polarization in ferroelectric thin films, Nature Materials 10, 963
(2011).
2
H. Lu et al, Mechanical Writing of Ferroelectric Polarization, Science 336, 59-61 (2012).
3
P. Zubko, G. Catalan, A. K. Tagantsev, Flexoelectric Effect in Solids, Annual Review of Materials
Research 43, 387 (2013).
4
Abdollahi et al, Fracture Toughening and Toughness Asymmetry Induced by Flexoelectricity, Phys. Rev.
Lett. (submitted).
Curriculum Vitae
Gustau Catalan graduated in Physics at the Universitat de Barcelona and got his
PhD, also in Physics, at Queen's University of Belfast (2001). This was followed
by research positions at the Mediterranean Institute for Advanced Studies, at the
University of Groningen and at the University of Cambridge.
Since 2009, he is an ICREA Research Professor and heads the Oxide
Nanoelectronics group at the Institut Catala de Nanociencia I Nanotecnologia
(ICN2) in Barcelona.
Prof. Catalan's research explores the functional properties of oxide electroceramics
at the nanoscale, with emphasis on strain coupling and phase transitions. Currently
the two main themes of his research are the effects of strain gradients on electrical
properties (flexoelectricity) and the physics and applications of domain walls
(domain wall nanoelectronics).