Least component-based delivery of drug-tagged-nanocarriers across blood-brain-barriers (BBB) will allow site-specific and on-demand release of therapeutics to prevent CNS diseases. We developed a non-invasive magnetically guided delivery of magneto-electric nanocarriers (MENCs), ~20 nm, 10 mg/kg, across BBB in C57Bl/J mice. Delivered MENCs were uniformly distributed inside the brain, and were non-toxic to brain and other major organs, such as kidney, lung, liver, and spleen, and did not affect hepatic, kidney and neurobehavioral functioning.

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An approach to fabrication of a patterned magnetic recording medium for next generation data storage systems is presented. (Co/Pd)n magnetic multilayers are evaluated as candidates for patterned medium materials for their high and easily controllable magnetic anisotropy. The multilayer films deposited on a Ta seed layer enable high intergranular exchange coupling—an essential feature of a patterned magnetic recording medium. The quality of (Co/Pd)n superlattices was optimized via deposition conditions and monitored using low-angle x-ray diffraction. An estimated in-plane (hard-axis) magnetization saturation field in excess of 40 000 Oe was observed. Vertical (easy-axis) hysteresis loops for as-deposited continuous magnetic multilayers exhibited a low coercivity of 930 Oe, indicating highly uniform (magnetically) films with weak domain wall pinning. Ion-beam proximity lithography was used to pattern magnetic multilayers into 43 nm islands on a 135 nm pitch. Following patterning, easy-axis coercivity increased nearly 15-fold to 12.7 kOe.

A 16.5 mm long, heavily doped erbium-ytterbium phosphate glass-waveguide amplifier was fabricated by the femtosecond laser (fs-laser) inscription technique. The femtosecond laser inscription of waveguides was carried out at 500 kHz repetition rate using a 0.68 NA aspheric lens. The energy deposition profile in the dielectric material was initially simulated using a generalized adaptive fast-Fourier evolver (GAFFE) algorithm. The size and shape of the guiding structures were carefully controlled by the slit shaping technique to reduce the coupling losses, with achievable values down to less than 0.1 dB. Rigorous simulations of the response of the active waveguides were carried out to optimize their performance as optical amplifiers. A maximum of 8.6 dB internal gain at 1534 nm was obtained upon bidirectional laser pumping at 976 nm, leading to a gain per unit length of 5.2 dB cm −1 . Laser action was also achieved for both ring and linear cavity configurations.

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We describe a self-limiting, low-energy argon-ion-milling process that enables noncircular device patterns, such as squares or hexagons, to be formed using precursor arrays of uniform circular openings in poly(methyl methacrylate) defined using electron beam lithography. The proposed patterning technique is of particular interest for bit-patterned magnetic recording medium fabrication, where square magnetic bits result in improved recording system performance. Bit-patterned magnetic medium is among the primary candidates for the next generation magnetic recording technologies and is expected to extend the areal bit density limits far beyond 1 Tbit/in(2). The proposed patterning technology can be applied either for direct medium prototyping or for manufacturing of nanoimprint lithography templates or ion beam lithography stencil masks that can be utilized in mass production.

In ion beam proximity lithography, ions that are incident on the nominally opaque regions of a stencil mask can scatter into the open windows and escape, exposing a wide area of the substrate. Since these ions can lose much of their initial energy in the mask, the scattered particle exposure is concentrated near the resist surface. The resulting loss of contrast can be mitigated to some extent by using aperture array lithography ͑AAL͒ where a mask of reduced density minimizes the number of windows from which a scattered ion can escape. Even so, the problem worsens as the pitch of an array, printed by multiple, offset exposures of the AAL mask, shrinks below about 250 nm. The only solution is to increase the mask thickness, hence the window aspect ratio, to reduce the escape angles of the scattered particles. In this article, the authors characterize an effective background dose in the first 75 nm of poly͑methylmethacrylate͒ resist for 30 keV He + ion exposures of 0.6 m thick masks with 45, 80, and 110 nm circular windows on 150, 300, and 400 nm pitches, respectively. They project that would be ͑6.8± 0.8͒ % ͑͒ of the primary ion dose for the printing of dense arrays, with period equal to twice the window diameter, over this range of feature sizes.

Conventional magnetic recording systems based on continuous medium recording are rapidly approaching their superparamagnetic limit. 1 A shift to patterned media 2 , where the data are stored in arrays of discrete nanomagnets, will help extend the areal bit densities due to a significant increase in the thermal activation volume. 3 One of the key challenges is the development of a costeffective strategy for media manufacturing. In this work, we present ion beam proximity lithography (IBPL) as a low cost tool for media patterning. (Co/Pd) n magnetic mutlilayers were used as a patterned medium material. Such magnetic multilayers exhibit very large and easily tunable vertical magnetic anisotropy 4 , which makes them suitable for ultra-high density magnetic recording applications. 5 The magnitude of the anisotropy can be varied by controlling the quality of the interfaces and/or by changing the thicknesses of the individual layers in the Co/Pd bi-layer stack. Also, an appropriate choice of a buffer/seed layer can help promote enhanced intergranular exchange coupling, an essential attribute of patterned medium materials. 6 Magnetic films were deposited by magnetron sputtering in 2.5mTorr Ar pressure at room temperature on silicon wafers coated with a 0.5µm thermal oxide. A 5nm Ta seed was used to promote exchangecoupled films. The deposition conditions and the thicknesses of individual Co (5.2Å) and Pd (6.6Å) layers were optimized to achieve the largest vertical anisotropy, smallest coercivity (to minimized domain wall pinning), and the remnant squareness of one. X-ray diffraction was used as a benchmarking tool to precisely gauge the period of the (Co/Pd) n superlattices and the thicknesses of individual Co and Pd layers (See Figure 1). Optimized films had a surface roughness of less than 1nm. Medium patterning was accomplished using IBPL 7 , a high-throughput direct write lithography where a large array of ion beamlets shaped by a stencil mask is used to write an arbitrary device pattern. In IBPL system used in this work, helium ions are extracted from a duo-plasmatron ion source and are then accelerated through a constant gradient tube towards a mask (silicon nitride stencil membrane) 8 as illustrated in Figure 2. A 30 keV He+ ion-beam with an ion current density of 140nA/cm 2 was used. HSQ, a high resolution negative tone resist 9 , was used for patterning. The sample was developed in 0.24N TMAH and the pattern was transferred into the multilayers using HSQ as the hard mask. Reactive ion etching (RIE) with CHF 3 was used to remove HSQ. SEM micrograph of a patterned medium prototype with 43nm features on a 135nm pitch and the vertical M-H loops for the continuous and patterned medium are shown in Figure 3. A 15x coercivity increase as a result of patterning can be observed. 1. H. N. Figure 3: (a) SEM micrograph of patterned medium sample and (b) Vertical M-H loops for continuous and patterned medium.Figure 1. (a) High angle x-ray measurements of multilayers with varying Co layer thickness in the (Co/Pd) n structure....