  The structural and ferroelectric domain variants of highly-strained BiFeO3
films grown on vicinal LaSrAlO4 substrates were studied by piezoelectric force
microscopy and high-resolution X-ray reciprocal space mapping. Through symmetry
breaking of the substrate surface, ferroelastic domain variants in the
highly-strained MC phase BiFeO3 can be greatly reduced. Single-domain film can
be obtained on substrates with large miscut angle, which is accompanied by the
reduction of structural variants in the mixed-phase nanodomains. These findings
lead to better understanding of the phase evolution and polarization rotation
process in the strain-driven morphotropic phase system.
