论文标题
沉积在Si底物上的Fe3O4薄膜的介电特性的温度和Terahertz频率依赖性
Temperature and terahertz frequency dependence of the dielectric properties of Fe3O4 thin films deposited on Si substrate
论文作者
论文摘要
由于高温磁过渡和半导体特性，Fe $ _3 $ o $ $ $ _4 $/SI膜被认为是THZ Spintronic应用的有前途的材料。在本文中，我们介绍了电介质常数（$ε_1$）的真实部分和Fe $ _3 $ _3 $ _3 $ o $ _4 $的光学电导率（$σ_1$）的真实部分NM在Verwey过渡温度t $ _v $ = 121 K处显示出明显的变化，其光学特性在THZ频率范围内彼此截然不同。我们已经证明，$σ_1$是最大值，$ε_1$是最低限度时，当fe $^{+2} $/fe $^{+3} $比率等于0.54，这是pure fe+2/fe+3的比率，而pu+2/fe+3的比率为pure fe $ $ _3 $ _3 $ o $ _4 $。当Fe $^{+2} $/fe $^{+3} $比率从0.54偏离时，$σ_1$减少，$ε_1$在所有温度下都会增加。我们已经表明，fe $^{+2} $/fe $^{+3} $比率的略有变化可能会引起光学特性的大型变化，这对在Thz spintronics中的应用中的应用有影响。
The Fe$_3$O$_4$/Si films are considered to be promising materials for THz spintronic applications due to their high temperature magnetic transition and semiconducting properties. In this article, we present the real part of the dielectric constant ($ε_1$) and the optical conductivity ($σ_1$) of Fe$_3$O$_4$ films of different thicknesses deposited on Si substrate (Fe$_3$O$_4$/Si) in the THz range at temperatures 2- 300 K. Although the magnetization of the films with thickness $\geq$ 115 nm shows a clear change at the Verwey transition temperature T$_v$ = 121 K, their optical properties in the THz frequency range are drastically different from each other. We have shown that $σ_1$ is maximum and $ε_1$ is minimum when the Fe$^{+2}$/Fe$^{+3}$ ratio is equal to 0.54 which is the ratio of Fe+2/Fe+3 for pure Fe$_3$O$_4$. The $σ_1$ reduces and $ε_1$ increases at all temperatures when the Fe$^{+2}$/Fe$^{+3}$ ratio deviates from 0.54. We have shown that a slight change in the Fe$^{+2}$/Fe$^{+3}$ ratio can induce large changes in the optical properties which shall have implications in the application of the Fe3O4 films in THz spintronics.
