Fig. 4: Polar homochiral Néel domain walls in BFO grown on BFTO.
From: Defeating depolarizing fields with artificial flux closure in ultrathin ferroelectrics
a, LPFM phase scan reveals [\(11\bar{1}\)]pc (P2) and [\(\bar{1}\bar{1}\bar{1}\)]pc (P1) as the only two in-plane polarization components in BFO when deposited on BFTO. b, VPFM phase scan shows a downward polarization across the film with only scattered local out-of-plane-polarized features. The associated PFM amplitude signals for a and b are shown in Supplementary Fig. 14. c, Schematic of the in-plane 109° HH and TT CDWs stabilized by the in-plane-polarized buffer. d,e, LPFM phase (d) and amplitude (e) scans show uniaxial in-plane-polarized BFO domains nucleated using the trailing field of a scanning probe tip. f, VPFM phase scan shows the out-of-plane polarization at the artificially created BFO domain walls (Supplementary Note 6 shows additional verification). Polarization rotation at the walls is identical to that of pristine domain walls (b): each HH wall exhibits a downward polarized state (black markers), whereas each TT wall is associated with an upward polarization (white markers), suggesting a uniform domain-wall chirality, as depicted in Fig. 5a. g, The VPFM amplitude increases at the HH walls and decreases at the TT walls. This reflects that the bottom BFTO layer favours a downward-oriented polarization and suppresses an upward-oriented polarization in the BFO layer.
