abstract
We consider nanoflakes of van der Waals ferrielectric CuInP2S6 covered by an ionic surface charge and reveal the appearance of polar states with a relatively large polarization of approximately 5 mu C/cm(2) and stored free charge of around 10 mu C/cm(2), which can mimic "midgap" states associated with a surface-fieldinduced transfer of Cu and/or In ions in the van der Waals gap. The change in the ionic screening degree and mismatch strains induce a broad range of the transitions between paraelectric phase, antiferroelectric, ferrielectric, and ferri-ionic states in CuInP2S6 nanoflakes. The states' stability and/or metastability is determined by the minimum of the system free energy consisting of electrostatic energy, elastic energy, and a Landau-type four-well potential of the ferrielectric dipole polarization. The possibility of governing the transitions by strain and ionic screening can be useful for controlling the tunneling barrier in thinfilm devices based on CuInP2S6 nanoflakes. Additionally, we predict that the CuInP2S6 nanoflakes reveal features of the controllable negative capacitance effect, which make them attractive for advanced electronic devices, such as nanocapacitors and gate oxide nanomaterials with reduced heat generation.
keywords
TEMPERATURE BEHAVIOR; TRANSITION
subject category
Physics
authors
Morozovska, AN; Kalinin, S; Eliseev, EA; Kopyl, S; Vysochanskii, YM; Evans, DR
our authors
Svitlana Kopyl
ResearcherProjects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
Piezoelectricity in 2D-materials: materials, modeling, and applications (Piezo2D)
acknowledgements
A.N.M. acknowledges EOARD project 9IOE063b and related STCU partner project P751b. This effort (problem statement and general analysis, S.V.K.) was supported as part of the Center for 3D Ferroelectric Microelectronics (3DFeM) , an Energy Frontier Research Center funded by the United States Department of Energy, Office of Science, Basic Energy Sciences under Award No. DE-SC0021118. The work of E.A.E. is supported by the United States Department of Energy Software Project on "Computational Mesoscale Science and Open Software forQuantum Materials", under Award No. DE-SC0020145 as part of the Computational Materials Sciences Program of United States Department of Energy, Office of Science, Basic Energy Sciences. This work of S.K. was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (Grant DOI: 10.54499/UIDB/50011/2020) , UIDP/50011/2020 (Grant DOI: 10.54499/UIDP/50011/2020) and LA/P/0006/2020 (Grant DOI10.54499/LA/P/0006/2020) , financed by national funds through the FCT/MCTES (PIDDAC) . Part of S.K.'s work was funded by national funds (OE) , through FCT: Fundacao para a Ciencia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of article 23, of the Decree-Law 57/2016, of 29 August, changed by Law 57/2017, of 19 July. Y.M.V. and S.K. acknowledge support from the Horizon Europe Framework Programme (HORIZON-TMA-MSCA-SE) , Project No. 101131229, Piezoelectricity in 2D-materials: materials, modeling, and applications (PIEZO 2D) . Numerical results were visualized in Mathematica 14.0 [69] .r Quantum Materials", under Award No. DE-SC0020145 as part of the Computational Materials Sciences Program of United States Department of Energy, Office of Science, Basic Energy Sciences. This work of S.K. was devel-oped within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (Grant DOI: 10.54499/UIDB/50011/2020) , UIDP/50011/2020 (Grant DOI: 10.54499/UIDP/50011/2020) and LA/P/0006/2020 (Grant DOI10.54499/LA/P/0006/2020) , financed by nati-onal funds through the FCT/MCTES (PIDDAC) . Part of S.K.'s work was funded by national funds (OE) , through FCT: Fundac & atilde;o para a Ciencia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of article 23, of the Decree-Law 57/2016, of 29 August, changed by Law 57/2017, of 19 July. Y.M.V. and S.K. acknowledge support from the Horizon Europe Framework Programme (HORIZON-TMA-MSCA-SE) , Project No. 101131229, Piezoelectric-ity in 2D-materials: materials, modeling, and applications (PIEZO 2D) . Numerical results were visualized in Mathe-matica 14.0 [69] . A.N.M. and S.V.K. generated the research idea, ana-lyzed results, and wrote the manuscript draft. A.N.M. formulated the problem and performed analytical calcula-tions. E.A.E. wrote the codes and prepared figures. S.V.K., Y.M.V., and D.R.E. worked on the results explanation and manuscript improvement. All coauthors discussed the results.