CHECKing Membranes And Twisted bilayer oxides for Exotic polar stabilization and Emergent phenomena in multifunctional nanomaterials – CHECKMATE

CHECKMATE aims to fabricate free-standing oxide membranes (OM) and twisted oxide bilayers (TOB) to explore emergent polarization phenomena. By engineering interfacial interactions between ferroelectric (FE) and antiferroelectric (AFE) materials, the project seeks to stabilize novel polar phases at the nanoscale, unlocking new properties for electronic and energy storage applications. The project unites three leading French laboratories—LPS (Université Paris-Saclay), SPMS (CentraleSupélec), and LAF (Université Paris-Saclay), with two expert groups from Taiwan (NTHU and NCKU). These teams bring together complementary expertise in advanced oxide thin film growth, structural characterization, and theoretical modeling, enabling a comprehensive exploration and further exploitation of twisted oxides bilayer.
Oxides films host diverse functionalities, including metal-insulator transitions (MIT) ((La,Ca)MnO3), ferro-electricity FE (PbTiO3, BaTiO3, BiFeO3), anti-ferro-electricity AFE (PbZrO3, PbSnO3, PbHfO3), and multiferroicity (BiFeO3). While conventional epitaxial thin films enable interface engineering, they are constrained by substrate clamping and lattice matching. CHECKMATE overcomes these limitations by fabricating free-standing OM and stacking them into twisted oxides bilayers, enabling precise control over interfacial coupling, strain, and symmetry breaking. State-of-the-art thin films will be grown via pulsed laser deposition, followed by chemical lift-off and transfer to form twisted structures. By taking advantage of Moiré engineering, the project will investigate how twist angles, post annealing, can fine-tune emergent properties. CHECKMATE will focus on FE-FE, FE-AFE, and AFE-AFE bilayers to explore exotic polarization textures and landscapes. We will search new properties resulting from the coupling of interactions at the nano scale, notably
- Inducing and controlling chiral polar textures in FE-FE bilayers (reported in 2024) or MIT-FE bilayers.
- Controlling electrical imprint effects in FE-AFE bilayers (analogous to exchange bias in magnetism)
- Exploring AFE-AFE bilayers for negative capacitance properties.
Advanced characterization techniques will provide insights for further interfaces management thanks to :
-4D-STEM and electron ptychography for high-resolution structural imaging,
- Correlative PFM-STEM for local polarization mapping,
- Synchrotron-based X-ray imaging techniques to probe ferroic orders interaction,
- Temperature-dependent studies (XRD, Raman, dielectric measurements) to track phase transitions,
A key challenge in CHECKMATE is understanding and controlling interfacial interactions. We will employ first-principles (ab initio) and second-principles (model Hamiltonian) simulations to predict phase stability, interlayer coupling, and Moiré-driven reconstructions.
Beyond fundamental discoveries, CHECKMATE will investigate practical applications of TOB: AFE-based capacitors offer high-density energy storage due to their large polarization difference and fast switching. Twisted bilayers could further enhance performance through optimized strain. A game-changer for low-power electronics, negative capacitance (NC) enables energy-efficient switching beyond the Boltzmann limit. AFE-AFE bilayers, with their complex energy landscapes, may provide extended NC regions with minimal hysteresis—an unexplored avenue with strong technological potential.
In summary, CHECKMATE pioneers a new frontier in oxide properties by harnessing Moiré engineering in twisted bilayer oxides. Through cutting-edge fabrication, advanced characterization, and theoretical modeling, the project will uncover novel polarization states and their technological applications. Through collaboration with the Taiwanese partners, the three French laboratories will gain valuable expertise in the fabrication of twisted bilayer oxides. CHECKMATE will position French teams among the leading researchers in the field of twisted oxides.