A multimodal scanning probe microscopy (SPM) approach reveals fast ionically mediated electromechanical coupling in the van der Waals ferroelectric CuInP2S6 (CIPS) along with an enhanced and tunable conductivity at chemical phase boundaries above the Curie temperature (Tc).
Significance and Impact
The tunable conductivity at the CIPS heterointerface with the Cu-free non-ferroelectric phase, In4/3P2S6(IPS), can be harnessed to impart novel 2D electronic, optoelectronic, electrocatalytic, and neuromorphic properties.
- Piezoresponse force microscopy (PFM) reveals ionically mediated electromechanical coupling in CIPS above Tc.
- Nanoscale dielectric imaging is used to map dielectric heterogeneities at the CIPS/IPS heterointerface.
- Density functional theory (DFT) calculations show that the presence of graded phase boundaries lowers the energy barrier for Cu transport from CIPS to IPS, explaining the enhanced ionic conductivity.