Abstract
Tailoring and enhancing the functional properties of materials at reduced dimension is critical for continuous advancement of modern electronic devices. Here, the discovery of local surface induced giant spontaneous polarization in ultrathin BiFeO3 ferroelectric films is reported. Using aberration-corrected scanning transmission electron microscopy, it is found that the spontaneous polarization in a 2 nm-thick ultrathin BiFeO3 film is abnormally increased up to ≈90–100 µC cm−2 in the out-of-plane direction and a peculiar rumpled nanodomain structure with very large variation in c/a ratios, which is analogous to morphotropic phase boundaries (MPBs), is formed. By a combination of density functional theory and phase-field calculations, it is shown that it is the unique single atomic Bi2O3 − x layer at the surface that leads to the enhanced polarization and appearance of the MPB-like nanodomain structure. This finding clearly demonstrates a novel route to the enhanced functional properties in the material system with reduced dimension via engineering the surface boundary conditions.
| Original language | English |
|---|---|
| Article number | 1701475 |
| Journal | Advanced Materials |
| Volume | 29 |
| Issue number | 30 |
| DOIs | |
| State | Published - Aug 11 2017 |
| Externally published | Yes |
Funding
L.X. and L.Z.L. contributed equally to this work. The work was supported by the Department of Energy (DOE), Office of Basic Energy Sciences (BES), Division of Materials Science and Engineering, under Grant No. DE-SC0014430 (L.X., L.Z.L., P.G., C.T.N. and X.Q.P.). The authors would like to acknowledge partial funding from the National Basic Research Program of China (Grant No. 2015CB654901) and the National Natural Science Foundation of China (Nos. 51302132 and 11474147) (L.X. and P.W.). The work at the Pennsylvania State University was supported by the DOE/BES, Division of Materials Science and Engineering, under Grant No. DE-FG02-07ER46417 (F.X. and L.Q.C.) and in part by the NSF under Grant No. DMR-1210588 (Z.H.). This work was also supported in part by NSF MRSEC under Grant No. DMR-1420620 (Y.Z. and F.X.). The work at Cornell University was supported by the DOE/BES, Division of Materials Sciences and Engineering, under Award No. DE-SC0002334 (C.A.H. and D.G.S.). The authors would also like to acknowledge the National Center for Electron Microscopy at Lawrence Berkeley National Laboratory for their support under the DOE Grant No. DE-AC02-05CH11231 for user facilities. This work was performed in part at the Cornell Nanoscale Facility, a member of the National Nanotechnology Infrastructure Network, which was supported by the National Science Foundation (Grant No. ECCS-0335765). This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility under Contract No. DE-AC02-05CH11231 (E.K.). The authors would like to acknowledge Dr. J. R. Jokisaari, Dr. G. W. Graham, Dr. H. D. Lu, and Prof. A. Gruverman for helpful discussions.
| Funders | Funder number |
|---|---|
| National Science Foundation | ECCS-0335765, DMR-1210588, 1210588 |
| U.S. Department of Energy | |
| Office of Science | |
| Basic Energy Sciences | |
| Division of Materials Sciences and Engineering | DE-AC02-05CH11231, DE-SC0014430, DE-SC0002334 |
| Materials Research Science and Engineering Center, Harvard University | DMR-1420620 |
| National Natural Science Foundation of China | DE-FG02-07ER46417, 11474147, 51302132 |
| National Key Research and Development Program of China | 2015CB654901 |
Keywords
- polarization
- scanning transmission electron microscopy
- surface effect
- ultrathin ferroelectric films