uFe2O4外延薄膜结构及磁性能与沉积气压的关系

uFe2O4 epitaxial thin films were deposited at 5 Pa, 10 Pa, 20 Pa, and 50 Pa in the ambient of Ar/O2(1:1) mixing gases on MgAl2O4(001) substrates by using RF magnetron sputtering method. The influences of deposition pressure of CFO epitaxial thin films on the microstructure and magnetic properties were studied. As the deposition pressure increases, the out-of-plane lattice, tetragonality, and unit cell volume all increase and the crystalline quality also improves. The CFO epitaxial thin film grown at 50 Pa possesses high tetragonality of 1.08 and keeps coherent growth mode. The M-H hysteresis loops at room temperature for all CFO thin films exhibit excellent soft magnetism with coercivity smaller than 50 Oe. The saturation magnetization of CFO films gradually increases as the deposition pressure increases. The deposition pressure dependent magnetization in CFO thin films can be understood by the deposition pressure induced cation redistribution. As the deposition pressure increases, the Cu2+ cations gradually emigrate from Tetrahedral sites (Td sites) to Octahedral sites (Oh sites), which suppresses the overall magnetism and reduce the unit cell volume of CFO thin films at the same time. This work demonstrates the deposition pressure has large impact on the cation distributions of CFO thin films, which could significantly modulate the magnetic properties.