Probing Ferroelectric Domain Engineering in BiFeO₃ Thin Films by Second Harmonic Generation

Abstract

An optical probe of the ferroelectric domain distribution and manipulation in BiFeO3 thin films is reported using optical second harmonic generation. A unique relation between the domain distribution and its integral symmetry is established. The ferroelectric signature is even resolved when the film is covered by a top electrode. The effect of voltage-induced ferroelectric switching is imaged.

Domain Wall Architecture in Tetragonal Ferroelectric Thin Films

“…Normally, the SHG intensity at Ising-like 180° domain walls drops to zero because of an interference effect: the SHG waves from opposite domain states exhibit a 180° phase difference, which leads to cancelation of these contributions when they are superimposing in the vicinity of the walls. [24,26] Figure 3a-c shows that the abnormal enhancement in the present study occurs at all the voltage-induced 180° c-domain walls of the tip-poled regions, yet with differently polarized SHG light from [110] DSO -and [001] DSO -oriented walls. SHG intensity enhancement induced by a reduction of symmetry has been reported at thermotropic phase boundaries in ferroelectric crystals.…”

Local twin domains and tip-voltage-induced domain switching of monoclinicMCphase inPb(Mg1/3Yang1, Luo2, Sun3 et al. 2016Phys. Rev. B163140View full textAdd to dashboardCite

“…In the past few years, the optical second harmonic generation (SHG) has been well established as an efficient tool to study the symmetry of the ferroelectrics, and has led to valuable insights on the monoclinic complex domain states [26,49,50]. Transmission electron microscopy (TEM) can achieve even higher resolution, but in situ electrical biasing TEM is difficult to perform and the stress state of the specimen may be changed during sample thinning process for TEM.…”

Evolution of structural distortion in BiFeO3 thin films probed by second-harmonic generation

“…Meanwhile, tremendous activities have been engaged to study BFO thin films, which may meet the needs for microelectronic information storage devices89101112. BFO thin films can exhibit different structural phases, including rhombohedral-like ( R -like) phase13, tetragonal-like ( T -like) phase14, fully relaxed bulklike rhombohedral ( R ) phase15, and even fully strained tetragonal ( T ) phase161718, depending on lattice mismatch and thermal expansion between films and different underlying substrates in the epitaxial growth progress. We speculate that the crystal structure of thin films may change from the substrate-like structure to an inclined bulklike character with the thickness of BFO thin films increasing gradually, due to the relaxation of strain, which may result in a symmetry change in BFO thin films71316.…”