resumo
Using Landau-Ginzburg-Devonshire (LGD) phenomenological approach we analyze the bending-induced redistribution 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 forces. The unique aspect of CIPS is the existence of two ferrielectric states, FI1 and FI2, corresponding to big and small polarization values, which arise due to the specific four-well potential of the eighth-order LGD functional. When the CIPS layer is flat, the single-domain FI1 state is stable in the central part of the layer, and the FI2 states are stable near the fixed edges. With an increase of the layer bending below the critical value, the sizes of the FI2 states near the fixed edges decreases, and the size of the FI1 region increases. When the bending exceeds the critical value, the edge FI2 states disappear being substituted by the FI1 state, but they appear abruptly near the inflection regions and expand as the bending increases. The bendinginduced isostructural FI1-FI2 transition is specific for the bended van der Waals ferrielectrics described by the eighth (or higher) order LGD functional with consideration of linear and nonlinear electrostriction couplings. The isostructural transition, which is revealed in the vicinity of room temperature, can significantly reduce the coercive voltage of ferroelectric polarization reversal in CIPS nanoflakes, allowing for the curvature-engineering control of various flexible nanodevices.
palavras-chave
PHASE-TRANSITIONS; CUINP2S6
categoria
Materials Science; Metallurgy & Metallurgical Engineering
autores
Morozovska, AN; Eliseev, EA; Liu, YT; Kelley, KP; Ghosh, A; Liu, Y; Morozovsky, NV; Yao, JY; Kholkin, AL; Vysochanskii, YM; Kalinin, SV
nossos autores
Andrei Kholkin
Investigador JubiladoProjectos
Piezoelectricity in 2D-materials: materials, modeling, and applications (Piezo2D)
agradecimentos
S.V.K., Y.L., and J.Y. are supported by the center for 3D Ferroelectric Microelectronics (3DFeM) , an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE) , Office of Science, Basic Energy Sciences under Award Number DE-SC0021118. A.N.M. acknowledges support from the National Research Fund of Ukraine (project "Low-dimensional graphene-like transition metal dichalcogenides with controllable polar and electronic properties for advanced nanoelectronics and biomedical applications", grant application 2020.02/0027) . E.A.E. and N.V.M. 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) . This work (A.L.K.) was developed within the scope of project CICECO-Aveiro Institute of Materials (UIDB/50011/2020 & UIDP/50011/2020) financed by national funds through the FCT-Foundation for Science and Technology (Portugal) .r 101131229, Piezoelectricity in 2D-materials: materials, modeling, and applications (PIEZO 2D) . This work (A.L.K.) was developed within the scope of project CICECO-Aveiro Institute of Materials (UIDB/50011/2020 & UIDP/50011/2020) financed by national funds through the FCT-Foundation for Science and Technology (Portugal) .