Growth, Structure and Magnetism of NiZnCu Ferrite Thin Films on SrTiO3, MgO and Glass Substrates
Date Issued
2007
Date
2007
Author(s)
Liu, Yu-Ting
Abstract
The structure of ferrite influences its magnetic and electric properties
significantly, and the growth process is crucial to the structural behaviors of ferrites.
Compared to bulk ferrites, there are more effects that could modify physical
properties in ferrite thin films.
In this work, we fabricate NiZnCu ferrite (NiZnCuFe2O4) thin films onto SrTiO3
(STO), MgO, and glass substrates by the magnetron RF sputtering technique in an
ultrahigh vacuum system. The influences of growth conditions on magnetic properties
and structures of NiZnCu ferrite thin films are studied. And the relations between the
magnetism and the structure are also investigated.
With the increase of substrate temperature, the spinel structure of NiZnCu ferrite
films is formed and the magnetic moment is enhanced. But this effect is obvious only
for films on STO. It reveals that compressive stress is conducive to the formation of
spinel ferrites. The addition of oxygen could reduce oxygen vacancies in NiZnCu
ferrite films under deposition. And we found a linear relation between the saturation
magnetization and the inverse of the film thickness. According to the linear relation,
we can predict that the NiZnCu thin film exceeds the bulk in the saturation
magnetization as the thickness of the film is reduced to 6 nm.
The coercivity and the remenance of films are greater than those of bulk ferrites
under any growth conditions. The saturation magnetization of films with thickness of
10 nm and substrate temperature of 650 ℃ achieves 75 % of the bulk value.
Subjects
鎳鋅銅亞鐵磁
薄膜
濺鍍
NiZnCu ferrite
thin film
sputter
Type
thesis
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