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Controlling the infrared (IR) emissivity of a photonic structure as a function of temperature is essential for regulating thermal emission. However, such self-adaptive radiative control often requires sophisticated fabrication processes to achieve the desired emissivity modulation, making large-scale implementation challenging. Here, we demonstrated a simple 1D photonic structure consisting of spin-coated VO2/ZnS/Al that does not require a costly vacuum deposition and/or lithography process for forming the active layer. Based on the phase change in VO2, over 50% modulation depth of peak emissivity was achieved in the atmospheric window. We also unraveled the optical constants of the solution-processed VO2 films using IR ellipsometry under temperature control, enabling realistic prediction of the emissive performance.

The recording performance of a new prototype magnetic tape based on perpendicularly oriented strontium ferrite particles is investigated using a 29 nm wide tunneling magnetoresistive reader. At a linear density of 702 kbpi, a post-detection byte-error rate of 2.8e-2 is demonstrated based on measured recording data and a software read channel. The read channel uses a 64-state implementation of an extended version of a data-dependent noise-predictive maximum-likelihood detection scheme that tracks the first and second order statistics of the data-dependent noise. At the demonstrated post-detection byte-error rate, a post-error-correction-coding byte-error rate of less than 1e-20 can be achieved using an iterative decoding architecture. To facilitate aggressive track-density scaling, we made multiple advances in the area of track following. First, we developed a new timing-based servo pattern and implemented a novel quad channel averaging scheme. Second, we developed a new field programmable gate array prototyping platform to enable the implementation of quad channel averaging. Third, we enhanced our low disturbance tape transport with a pair of 20 mm diameter air bearing tape guides and a prototype track-following actuator. Fourth, we developed a novel low friction tape head and finally, we designed a set of tape speed optimized track-following controllers using the model-based H∞ design framework. Combining these technologies, we achieved a position error signal (PES) characterized by a standard deviation ≤ 3.18 nm over a tape speed range of 1.2 to 4.1 m/s. This magnitude of PES in combination with a 29 nm wide reader enables reliable recording at a track width of 56.2 nm corresponding to a track density of 451.9 ktpi, for an equivalent areal density of 317.3 Gb/in2.

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.

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.

Protonated forms of layered perovskites were derived from Aurivillius phases, Bi2ANaNb3O12 (A = Sr or Ca), by the substitution of bismuth oxide sheets with protons via acid treatment. The conversion into the protonated forms was achieved easily using 6 M HCl at room temperature. Preservation of the structure of the perovskite-like slabs and contraction in the c axis were confirmed by X-ray and electron diffraction analysis as well as by transmission electron microscopy. The compositions of the resulting products were determined to be H1.8[A0.8Bi0.2NaNb3O10] (A = Sr or Ca) by inductively coupled plasma emission spectroscopy and thermogravimetry. The acid-treated product H1.8[Sr0.8Bi0.2NaNb3O10] was capable of accommodating n-alkylamines in the interlayer space, which is in good agreement with the proposed layered structure.

An Aurivillius phase, Bi(2)SrTa(2)O(9), which consists of perovskite-like slabs and bismuth oxide sheets, was treated with 3 M hydrochloric acid for 72 h, and the resultant product was characterized. Scanning electron microscopy investigation indicated that no morphological change occurred during the acid treatment. X-ray diffraction (XRD) analysis revealed that the product exhibited tetragonal symmetry with a = 0.391 +/- 0.004 nm and c = 0.98 +/- 0.01 nm, and the a parameter is consistent with a typical value for cubic perovskite oxides. High-resolution electron microscopy (HREM) observations along both [001] and [010] showed that the structure of the perovskite-like slabs in Bi(2)SrTa(2)O(9) was retained after the acid treatment. The compositional analyses revealed the loss of a large portion of bismuth and a part of strontium (present in the bismuth oxide sheets due to B Sr disorder) and the introduction of protons. These observations indicate that the bismuth oxide sheets in Bi(2)SrTa(2)O(9) were selectively leached and that protons were introduced into the interlayer space to form a protonated layered perovskite, H(1.8)[Sr(0.8)Bi(0.2)Ta(2)O(7)]. Though diffraction techniques (XRD and electron diffraction) demonstrated that an average structure of H(1.8)[Sr(0.8)Bi(0.2)Ta(2)O(7)] consisted of perovskite-like slabs stacked without displacement, HREM observation along [010] demonstrated that both a simple stacking sequence without displacement (P-type) and a stacking sequence with a relative displacement by (a + b)/2 (I-type) were present in H(1.8)[Sr(0.8)Bi(0.2)Ta(2)O(7)].

Carrier doping in Sr n+1 Ti n O 3n+1 (n = 1, 2) was conducted by the substitution of La for Sr and the simultaneous introduction of oxygen vacancies. Single-phase products of (Sr 0.95 La 0.05 ) n+1 Ti n O 3n+1-δ (n = 1, δ = 0.05; n = 2, δ = 0.125) were synthesized by the solid-state reaction of Sr 2 TiO 4 (or Sr 3 Ti 2 O 7 ), La 2 O 3 and Ti. When TiO 2 was used as one of the starting compounds to maintain oxygen stoichiometry, compounds with higher n were observed besides the object phases. Structural refinement by Rietveld analysis revealed that the a-axis expands while the c-axis contracts with La doping. The contraction of the c-axis is attributed to a shortened (Sr,La)-O distance. since the TiO 6 octahedra elongated in both a and c directions with doping. The change in the structure is discussed on the basis of the size of the substituting ion. The resistivity of the single-phase products was semiconducting with a very weak temperature dependence down to 80 K.

Protonated forms of layered perovskites were derived from Aurivillius phases, Bi2ANaNb3O12 (A = Sr or Ca), by the substitution of bismuth oxide sheets with protons via acid treatment. The conversion into the protonated forms was achieved easily using 6 M HCl at room temperature. Preservation of the structure of the perovskite-like slabs and contraction in the c axis were confirmed by X-ray and electron diffraction analysis as well as by transmission electron microscopy. The compositions of the resulting products were determined to be H1.8[A0.8Bi0.2NaNb3O10] (A = Sr or Ca) by inductively coupled plasma emission spectroscopy and thermogravimetry. The acid-treated product H1.8[Sr0.8Bi0.2NaNb3O10] was capable of accommodating n-alkylamines in the interlayer space, which is in good agreement with the proposed layered structure.

A protonated form of a layered perovskite was prepared from an Aurivillius phase Bi2SrNaNb3O12via acid treatments, and the effect of the type of mineral acids was investigated. The treatment with HX (X = Cl, Br, I) resulted in the formation of a protonated form H1.8[Sr0.8Bi0.2NaNb3O10], while no reactions were observed for HNO3 and H2SO4 under the present experimental conditions. All the products obtained by HX-treatments exhibited layered structures and the structures of the perovskite-like slabs were preserved.