Thickness dependence of the structure and magnetization of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Bi</mml:mi><mml:mi mathvariant="normal">Fe</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>thin films on<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mo>(</mml:mo><mml:mi mathvariant="normal">La</mml:mi><mml:mi mathvariant="normal">Al</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:mo>)</mml:mo></mml:mrow><mml:mn>0.3</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mo>(</mml:mo><mml:msub><mml:mi mathvariant="normal">Sr</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi mathvariant="normal">Al</mml:mi><mml:mi mathvariant="normal">Ta</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>6</mml:mn></mml:msub><mml:mo>)</mml:mo></mml:mrow><mml:mn>0.7</mml:mn></mml:msub></mml:mrow></mml:math>(001) substrate

The structural dependence of magnetization in $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$ thin films deposited on ${(\mathrm{La}\mathrm{Al}{\mathrm{O}}_{3})}_{0.3}{({\mathrm{Sr}}_{2}\mathrm{Al}\mathrm{Ta}{\mathrm{O}}_{6})}_{0.7}$ (001) substrate has been investigated in the film thickness $(t)$ range of $40--500\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$. High-resolution x-ray-diffraction studies reveal a thickness dependent structural transition from a fully strained tetragonal phase for films with $t\ensuremath{\leqslant}75\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ to a partially strained and/or relaxed rhombohedral phase in films thicker than $110\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$, via a coexistence of fully and partially strained phases in the thickness of $75&gt;t&gt;110\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$. The fully strained phase could also be partially induced in $110\text{\ensuremath{-}}\mathrm{nm}$ films by increasing the post-deposition ${\mathrm{O}}_{2}$ annealing pressure. The films $\ensuremath{\geqslant}110\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ were found to possess a thickness independent bulklike magnetic moment. A weak enhancement in magnetic moment (up to $\ensuremath{\sim}0.1{\ensuremath{\mu}}_{\mathrm{B}}$) is observed in fully strained films $(t\ensuremath{\leqslant}75\phantom{\rule{0.3em}{0ex}}\mathrm{nm})$ and in excessive ${\mathrm{O}}_{2}$-annealed $110\text{\ensuremath{-}}\mathrm{nm}$ films having a fraction of strained phase. These results suggest that by a considerably weak magnetic moment in the pseudomorphic strained phase arises from the epitaxial strain induced canted antiferromagnetic structure. This study resolves a much debated issue of strain induced magnetic moment in $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$ thin films.