Magnetic Properties of Polycrystalline Bismuth Ferrite Thin Films Grown by Atomic Layer Deposition.
The atomic layer deposition (ALD) method was applied to grow thin polycrystalline BiFeO3 (BFO) films on Pt/SiO2/Si substrates. The 50 nm thick films were found to exhibit high resistivity, good morphological integrity, and homogeneity achieved by the applied ALD technique. Magnetic characterization revealed saturated magnetization of 25 emu/cm(3) with temperature-dependent coercivity varying from 5 to 530 Oe within the temperature range from 300 to 2 K. Magnetism observed in the films was found to change gradually from ferromagnetic spin ordering to pinned magnetic domain interactions mixed with weak spin-glass-like behavior of magnetically frustrated antiferromagnetic/ferromagnetic (AFM-FM) spin ordering depending on the temperature and magnitude of the applied magnetic field. Antiferromagnetic order of spin cycloids was broken in polycrystalline films by crystal sizes smaller than the cycloid length (∼60 nm). Uncompensated spincycloids and magnetic domain walls were found to be the cause of the high magnetization of the BFO films.
†Department of Physics, Division of Materials Physics, University of Helsinki, P.O. Box 43, FI-00014, Helsinki, Finland.
Pasi
P
Jalkanen
†Department of Physics, Division of Materials Physics, University of Helsinki, P.O. Box 43, FI-00014, Helsinki, Finland.
Vladimir
V
Tuboltsev
†Department of Physics, Division of Materials Physics, University of Helsinki, P.O. Box 43, FI-00014, Helsinki, Finland.
Benoît
B
Marchand
‡School of Science, O.V. Lounasmaa Laboratory, Aalto University, P.O. Box 15100, FI-00076, Espoo, Finland.
Alexander
A
Savin
§Department of Chemistry, Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland.
Manjunath
M
Puttaswamy
§Department of Chemistry, Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland.
Marko
M
Vehkamäki
†Department of Physics, Division of Materials Physics, University of Helsinki, P.O. Box 43, FI-00014, Helsinki, Finland.
Kenichiro
K
Mizohata
§Department of Chemistry, Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland.
Marianna
M
Kemell
§Department of Chemistry, Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland.
Timo
T
Hatanpää
∥Structural Materials Technology Faculty, Volgograd State Technical University, RU-400005, Volgograd, Russia.
Valentin
V
Rogozin
†Department of Physics, Division of Materials Physics, University of Helsinki, P.O. Box 43, FI-00014, Helsinki, Finland.
Jyrki
J
Räisänen
§Department of Chemistry, Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland.
Mikko
M
Ritala
§Department of Chemistry, Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland.
Markku
M
Leskelä
domain wall pinning; ferromagnetism; multiferroics; perovskites; spin glass