Abstract
The impact of single-axis lattice expansion on the optical response of BiFeO3 films is examined. Low-energy He implantation is used to tailor morphotropic phases of BiFeO3 films and study changes in their optical spectra with continuously increasing lattice expansion. He ion implantation of epitaxial rhombohedral (R)- A nd tetragonal (T)-like BiFeO3 films induces uniaxial out-of-plane strain that, on R-like films, eventually leads to a complete R-T phase transition. This approach allows us to provide insights into the optical response of BiFeO3 films. Strain doping of T-like films leads to a significant redshift of the optical absorption spectra that is theoretically explained by a lowering of Fe 3dt2g states. R-like films, on the other hand, show a less-pronounced sensitivity to uniaxial strain and a blueshift of about 250 meV at the strain-induced R-T transition. The results demonstrate that strain doping allows a deeper examination of the optical properties of epitaxial phases that are otherwise impossible to access by standard epitaxy.
| Original language | English |
|---|---|
| Article number | 094410 |
| Journal | Physical Review Materials |
| Volume | 3 |
| Issue number | 9 |
| DOIs | |
| State | Published - Sep 23 2019 |
Funding
Experiment design, sample synthesis, strain modification and structural characterization were supported by the US Department of Energy (DOE), Office of Basic Energy Sciences (BES), Materials Sciences and Engineering Division and Quantum Condensed Matter Division. Ellipsometry completed by S.F.R. was financially supported by National Authority for Scientific Research and Innovation (ANCSI) within PN 16 14 03 02 contract and mobility grants of the Romanian Ministry of Research and Innovation, Grants No. CNCS – UEFISCD MC-2018-0561 and No. MC-2017-0791. A.H. was supported by the Deutsche Forschungsgemeinschaft, Grant No. SFB 762, Functional Oxide Interfaces.