ABSTRACT
Active control of optical properties, particularly in the infrared (IR) regime, is critical for the regulation of thermal emission. However, most photonic structures and devices are based on a sophisticated design, making the dynamic control of their IR properties challenging. Here, we demonstrate self-adaptive control of IR absorptivity/emissivity in a simple stacked structure that consists of an oxide plasmonic nanocrystal layer and a phase change material (VO2) layer, both fabricated via a solution process. The resonance wavelength and emission intensity for this structure depend on the phase of the VO2. This has potential applications for thermal emission structures (e.g., self-adaptive radiative cooling and IR camouflage). The proposed structure is a candidate low-cost and scalable active photonic platform.
ABSTRACT
In the era of Big Data and the Internet of Things, data archiving is a key technology. From this viewpoint, magnetic recordings are drawing attention because they guarantee long-term data storage. To archive an enormous amount of data, further increase of the recording density is necessary. Herein a new magnetic recording methodology, "focused-millimeter-wave-assisted magnetic recording (F-MIMR)," is proposed. To test this methodology, magnetic films based on epsilon iron oxide nanoparticles are prepared and a focused-millimeter-wave generator is constructed using terahertz (THz) light. Irradiating the focused millimeter wave to epsilon iron oxide instantly switches its magnetic pole direction. The spin dynamics of F-MIMR are also calculated using the stochastic Landau-Lifshitz-Gilbert model considering all of the spins in an epsilon iron oxide nanoparticle. In F-MIMR, the heat-up effect of the recording media is expected to be suppressed. Thus, F-MIMR can be applied to high-density magnetic recordings.
