Article 1 – The strain-induced transitions of the piezoelectric, pyroelectric, and electrocaloric properties of the CuInP2S6 films

Abstract:

Low-dimensional ferroelectrics, ferrielectrics, and antiferroelectrics are of urgent scientific interest due to their unusual polar, piezoelectric, electrocaloric, and pyroelectric properties. The strain engineering and strain control of the ferroelectric properties of layered two-dimensional van der Waals materials, such as CuInP₂(S,Se)₆ monolayers, thin films, and nanoflakes, are of fundamental interest and especially promising for their advanced applications in nanoscale nonvolatile memories, energy conversion and storage, nano-coolers, and sensors. Here, we study the polar, piezoelectric, electrocaloric, and pyroelectric properties of thin strained films of a ferrielectric CuInP₂S₆ covered by semiconducting electrodes and reveal an unusually strong effect of a mismatch strain on these properties. In particular, the sign of the mismatch strain and its magnitude determine the complicated behavior of piezoelectric, electrocaloric, and pyroelectric responses. The strain effect on these properties is opposite, i.e., “anomalous,” in comparison with many other ferroelectric films, for which the out-of-plane remanent polarization, piezoelectric, electrocaloric, and pyroelectric responses increase strongly for tensile strains and decrease or vanish for compressive strains.

Title: The strain-induced transitions of the piezoelectric, pyroelectric, and electrocaloric properties of the CuInP2S6 films

Authors: Anna N. Morozovska, Eugene A. Eliseev, Lesya P. Yurchenko, Valentyn V. Laguta, Yongtao Liu, Sergei V. Kalinin, Andrei L. Kholkin, Yulian M. Vysochanskii

Reference: AIP Advances 13, 125306 (2023)

DOI: https://doi.org/10.1063/5.0178854

Article 6 – Tunable Ferroionic Properties in CeO2/BaTiO3 Heterostructures

2024-09-17

Abstract: Ferroionic materials combine ferroelectric properties and spontaneous polarization with ionic phenomena of fast charge recombination and electrodic functionalities. In this paper, we propose the concept of tunable polarization in CeO2−δ (ceria) thin (5 nm) films induced by built-in remnant polarization of a BaTiO3 (BTO) ferroelectric thin film interface, which

Article 5 – Size Effect of Negative Capacitance State and Subthreshold Swing in Van der Waals Ferrielectric Field-Effect Transistors

2024-01-11

Abstract: Analytical calculations corroborated by the finite element modelling show that thin films of Van der Waals ferrielectrics covered by a 2D-semiconductor are promising candidates for the controllable reduction of the dielectric layer capacitance due to the negative capacitance (NC) effect emerging in the ferrielectric film. The NC state is

Article 4 – Ferri-ionic Coupling in CuInP2S6 Nanoflakes: Polarization States and Controllable Negative Capacitance

2024-01-11

Abstract: We consider nanoflakes of van der Waals ferrielectric CuInP2S6 covered by an ionic surface charge and reveal the appearance of polar states with relatively high polarization ~5 microC/cm2 and stored free charge ~10 microC/cm, which can mimic „mid-gap” states associated with a surface field-induced transfer of Cu and/or In ions in

Article 3 – Strain-polarization coupling in the low-dimensional Van der Waals Ferrielectrics

2024-01-11

Abstract: Using the Landau-Ginzburg-Devonshire phenomenological approach we explore the strain-polarization coupling in the low-dimensional van der Waals ferrielectrics. We evolve the analytical model of the piezoelectric susceptibility of the material in response to the periodic strain modulation, such as caused by a surface acoustic wave. Numerical calculations are performed for

Article 2 – Bending-induced isostructural transitions in ultrathin layers of van der Waals ferrielectrics

2024-01-10

Abstract: Using Landau-Ginzburg-Devonshire (LGD) phenomenological approach we analyze the bending-induced re-distribution of electric polarization and field, elastic stresses and strains inside ultrathin layers of van der Waals ferrielectrics. We consider a CuInP2S6 (CIPS) thin layer with fixed edges and suspended central part, the bending of which is induced by external