| AVS 61st International Symposium & Exhibition | |
| 2D Materials Focus Topic | Thursday Sessions |
| Session 2D+EM+MI+MN+NS+SS+TF-ThA |
| Session: | Novel Quantum Phenomena in 2D Materials |
| Presenter: | Alex Belianinov, Oak Ridge National Laboratory |
| Authors: | A. Belianinov, Oak Ridge National Laboratory P. Maksymovych, Oak Ridge National Laboratory A. Dziaugys, Vilnius University, Lithuania Q. He, Oak Ridge National Laboratory E. Eliseev, National Academy of Sciences of Ukraine A,. Borisevich, Oak Ridge National Laboratory A. Morozovska, NAS of Ukraine J. Banys, Vilnius University, Lithuania Y. Vysochanskii, Uzhgorod University, Ukraine S.V. Kalinin, Oak Ridge National Laboratory |
| Correspondent: | Click to Email |
We have utilized ambient and Ultra High Vacuum Scanning Probe Microscopy tools to explore ferroelectric properties in cleaved 2D flakes of copper indium thiophosphate, CuInIIIP2S6 (CITP), and report on size effect and presently achievable limits of ferroelectric phase stability. CITP is an unusual example of a layered, anti-collinear, uncompensated, two-sublattice ferroelectric system. These are the only materials known to display “2-D” ferroelectric semiconductor behavior in a van-der-Waals crystal. The material exhibits a first-order phase transition of order–disorder type from the paraelectric to the ferrielectric phase at Tc = 315 K. Our observations suggest the presence of stable ferroelectric polarization as evidenced by domain structures, rewritable polarization, and hysteresis loops. These observations suggest that flakes above 100 nm have bulk-like polarization and domain structures, whereas below 50 nm polarization disappears. Furthermore, the materials have measurable ionic mobility, as evidenced both by macroscopic measurements and by formation of surface damage above tip bias of 4 V, likely due to copper reduction. We ascribe this behavior to well-known instability of polarization due to depolarization field, along with internal screening by mobile Cu ions, as suggested by their high ionic mobility.
Acknowledgement:
Research for (AB, PM, QH, AB, SVK) was supported by the US Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division. Research was conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy.