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Flexocoupling impact on size effects of piezoresponse and conductance in mixed-type ferroelectric semiconductors under applied pressure

Morozovska, Anna N. and Eliseev, Eugene A. and Genenko, Yuri A. and Vorotiahin, Ivan S. and Silibin, Maxim V. and Cao, Ye and Kim, Yunseok and Glinchuk, Maya D. and Kalinin, Sergei V. (2016):
Flexocoupling impact on size effects of piezoresponse and conductance in mixed-type ferroelectric semiconductors under applied pressure.
In: Physical Review B, pp. 174101(1, 94, (17), ISSN 2469-9950,
[Online-Edition: http://dx.doi.org/10.1103/PhysRevB.94.174101],
[Article]

Abstract

We explore the role of flexoelectric effect in functional properties of nanoscale ferroelectric films with mixed electronic-ionic conductivity. Using a coupled Ginzburg-Landau model, we calculate spontaneous polarization, effective piezoresponse, elastic strain and compliance, carrier concentration, and piezoconductance as a function of thickness and applied pressure. In the absence of flexoelectric coupling, the studied physical quantities manifest well-explored size-induced phase transitions, including transition to paraelectric phase below critical thickness. Similarly, in the absence of external pressure flexoelectric coupling affects properties of these films only weakly. However, the combined effect of flexoelectric coupling and external pressure induces polarizations at the film surfaces, which cause the electric built-in field that destroys the thickness-induced phase transition to paraelectric phase and induces the electretlike state with irreversible spontaneous polarization below critical thickness. Interestingly, the built-in field leads to noticeable increase of the average strain and elastic compliance in this thickness range. We further illustrate that the changes of the electron concentration by several orders of magnitude under positive or negative pressures can lead to the occurrence of high- or low-conductivity states, i.e., the nonvolatile piezoresistive switching, in which the swing can be controlled by the film thickness and flexoelectric coupling. The obtained theoretical results can be of fundamental interest for ferroic systems, and can provide a theoretical model for explanation of a set of recent experimental results on resistive switching and transient polar states in these systems.

Item Type: Article
Erschienen: 2016
Creators: Morozovska, Anna N. and Eliseev, Eugene A. and Genenko, Yuri A. and Vorotiahin, Ivan S. and Silibin, Maxim V. and Cao, Ye and Kim, Yunseok and Glinchuk, Maya D. and Kalinin, Sergei V.
Title: Flexocoupling impact on size effects of piezoresponse and conductance in mixed-type ferroelectric semiconductors under applied pressure
Language: English
Abstract:

We explore the role of flexoelectric effect in functional properties of nanoscale ferroelectric films with mixed electronic-ionic conductivity. Using a coupled Ginzburg-Landau model, we calculate spontaneous polarization, effective piezoresponse, elastic strain and compliance, carrier concentration, and piezoconductance as a function of thickness and applied pressure. In the absence of flexoelectric coupling, the studied physical quantities manifest well-explored size-induced phase transitions, including transition to paraelectric phase below critical thickness. Similarly, in the absence of external pressure flexoelectric coupling affects properties of these films only weakly. However, the combined effect of flexoelectric coupling and external pressure induces polarizations at the film surfaces, which cause the electric built-in field that destroys the thickness-induced phase transition to paraelectric phase and induces the electretlike state with irreversible spontaneous polarization below critical thickness. Interestingly, the built-in field leads to noticeable increase of the average strain and elastic compliance in this thickness range. We further illustrate that the changes of the electron concentration by several orders of magnitude under positive or negative pressures can lead to the occurrence of high- or low-conductivity states, i.e., the nonvolatile piezoresistive switching, in which the swing can be controlled by the film thickness and flexoelectric coupling. The obtained theoretical results can be of fundamental interest for ferroic systems, and can provide a theoretical model for explanation of a set of recent experimental results on resistive switching and transient polar states in these systems.

Journal or Publication Title: Physical Review B
Volume: 94
Number: 17
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Materials Modelling
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 16 Dec 2016 09:35
Official URL: http://dx.doi.org/10.1103/PhysRevB.94.174101
Identification Number: doi:10.1103/PhysRevB.94.174101
Funders: E.A.E. and A.N.M. acknowledge the National Academy of Sciences of Ukraine (Grant No. 07-06-15) and Grant No. CNMS2016-061. S.V.K. acknowledges the Office of Basic Energy Sciences, U.S. Department of Energy. I.S.V. is grateful to the German Research, Foundation for support through Grant No. GE 1171/7-1. M.V.S. acknowledges the grant of the President of the Russian Federation for state support of young Russian scientists—Ph.D. (Grant No. 14.Y30.15.2883-MK) and the project part of the state tasks in the, field of scientific activity Grant No. 11.2551.2014/K. Y.K. acknowledges that a portion of this work was supported by the Basic Science Research program through the National Research Foundation of Korea funded by the Ministry of Science, ICT and Future, Planning (Grant No. NRF-2014R1A4A1008474).
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