论文标题
朝向形态学诱导的各向异性二氧化钒的热滞后介电特性
Towards Morphologically Induced Anisotropy in Thermally Hysteretic Dielectric Properties of Vanadium Dioxide
论文作者
论文摘要
Bruggeman均质化形式主义用于研究由二氧化钒制成的柱状薄膜（CTF）的介电性能。对于可见的和近红外的波长，CTF在电磁上等同于均匀的正交物质。在58度C -72度C温度范围内，CTF相对介电常数二元的特征值对温度高度敏感，并且根据CTF是否被加热或冷却而变化。通过特征值揭示的各向异性，并研究了相关滞后的各向异性，与不同孔隙率和柱状横截面的CTF的温度有关。当自由空间波长为800 nm时，CTF是一种耗散介电材料，表现出温度依赖性各向异性和各向异性滞后滞后。相反，当自由空间波长为1550 nm时，CTF可以是耗散介电材料，双曲线材料或类似金属的材料，具体取决于CTF的温度和孔隙率。随着CTF的孔隙率从0.55降低到0.3，CTF的各向异性变得更加明显，磁滞的各向异性也变得更加明显。与因改变孔隙率而引起的变化相比，仅在改变柱状横截面形状的各向异性和滞后时出现相对适度的变化。
The Bruggeman homogenization formalism was used to numerically investigate the dielectric properties of a columnar thin film (CTF) made from vanadium dioxide. For visible and near-infrared wavelengths, the CTF is electromagnetically equivalent to a homogeneous orthorhombic material. Over the 58 deg C -- 72 deg C temperature range, the eigenvalues of the CTF's relative permittivity dyadic are highly sensitive to temperature, and vary according to whether the CTF is being heated or cooled. The anisotropy revealed through the eigenvalues, and the anisotropy of the associated hysteresis, were investigated in relation to temperature for CTFs of different porosities and columnar cross sections. When the free-space wavelength is 800 nm, the CTF is a dissipative dielectric material that exhibits temperature-dependent anisotropy and anisotropic hysteresis. In contrast, when the free-space wavelength is 1550 nm, the CTF can be either a dissipative dielectric material, a hyperbolic material or a metal-like material, depending on the temperature and the porosity of the CTF. As the porosity of the CTF decreases from 0.55 to 0.3, the anisotropy of the CTF becomes more pronounced, as does the anisotropy of the hysteresis. Only relatively modest variations in anisotropy and hysteresis arise in response to varying the columnar cross-sectional shape, as compared to the variations induced by varying the porosity.
