The Ferroelectric and Magnetic Properties of Sol-Gel-Derived (Bi$_{0.85}$ Eu$_{0.15}$ FeO$_{3}$ /Bi$_{3.2}$ Y$_{0.8}$ Ti$_{3}$ O$_{12}$ ) Bilayer Thin Films

The Bi
_0.85
Eu
_0.15
FeO
₃
/Bi
_3.2
Y
_0.8
Ti
₃
O
₁₂
bilayer thin films were prepared on Pt(111)/Ti/SiO
₂
/Si(100) substrates using the sol-gel process and annealed by rapid thermal annealing in various annealing environments (ambient atmosphere and oxygen). The multiferroic/ferroelectric bilayer thin films were composed of 0.8-μ m thickness Bi
_0.85
Eu
_0.15
FeO
₃
and 0.2-μ m thickness of Bi
_3.2
Y
_0.8
Ti
₃
O
₁₂
thin film. The effects of annealing atmospheres (ambient atmosphere and oxygen) on the growth and properties of thin films were investigated. The results show that the intensities of the (117) diffraction peak of Bi
_3.2
Y
_0.8
Ti
₃
O
₁₂
film and (110) diffraction peak of Bi
_0.85
Eu
_0.15
FeO
₃
annealed in oxygen is stronger than those annealed in an ambient atmosphere. The Bi
_0.85
Eu
_0.15
FeO
₃
/Bi
_3.2
Y
_0.8
Ti
₃
O
₁₂
bilayer thin films annealed in the oxygen atmosphere exhibit the maximum remanent polarization (2\mbi
P
_r
) and remnant magnetization (2Mr) of 26 μ C/cm
²
and 3.44 emu/g, respectively. The improved magnetic and ferroelectric properties can be attributed to the elimination of defects, such as oxygen vacancy and vacancy complexes.