Using electron beam nanolithography and electroplating, arrays of Ni pillars on silicon that have a uniform diameter of 35 nm, a height of 120 nm, and a period of 100 nm were fabricated. The density of the pillar arrays is 65 Gbits/in.2-over two orders of magnitude greater than the state-of-the-art magnetic storage density. Because of their nanoscale size, shape anisotropy, and separation from each other, each Ni pillar is single domain with only two quantized perpendicular magnetization states: up and down. Each pillar can be used to store one bit of information, therefore such nanomagnetic pillar array storage offers a rather different paradigm than the conventional storage method. A quantum magnetic disk scheme that is based on uniformly embedding single-domain magnetic structures in a nonmagnetic disk is proposed.

Channelrhodopsins (ChRs) are algal light-gated ion channels widely used as optogenetic tools for manipulating neuronal activity. ChRs desensitize under continuous bright-light illumination, resulting in a significant decline of photocurrents. Here we describe a metagenomically identified family of phylogenetically distinct anion-conducting ChRs (designated MerMAIDs). MerMAIDs almost completely desensitize during continuous illumination due to accumulation of a late non-conducting photointermediate that disrupts the ion permeation pathway. MerMAID desensitization can be fully explained by a single photocycle in which a long-lived desensitized state follows the short-lived conducting state. A conserved cysteine is the critical factor in desensitization, as its mutation results in recovery of large stationary photocurrents. The rapid desensitization of MerMAIDs enables their use as optogenetic silencers for transient suppression of individual action potentials without affecting subsequent spiking during continuous illumination. Our results could facilitate the development of optogenetic tools from metagenomic databases and enhance general understanding of ChR function.

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This article reports the fabrication and preliminary photoluminescence (PL) study of free-standing Si pillars with diameters of about 10 nm and aspect ratios greater than 15. The pillars were fabricated using electron-beam lithography, chlorine based reactive ion etching (RIE), and subsequent HF wet etching. Using HF etching offers several advantages: (a) it is a relatively stress independent process and therefore preserves the original shape of the structure; (b) it is a room temperature process; (c) it has a very controllable etch rate, ∼1.9 nm/h; and (d) it can remove RIE damage and passivate the Si surface. PL with a peak at 720 nm was repeatedly observed from an array of nanoscale pillars with ∼20 nm diameters. However, the cause of such PL is still unclear.

Articles you may be interested inCombined atomic force microscope and electron-beam lithography used for the fabrication of variable-coupling quantum dots A novel magnetic force microscope tip has been proposed and fabricated that consists of a -30 nm thick ferromagnetic film coated on one side of a nonmagnetic pillar which is -150 nm wide and over 1.5 lim long. The pillar was fabricated on the apex of a commercial scanning force microscope tip using high-resolution electron beam lithography. The ferromagnetic film was evaporated on the pillar from an angle so that only the pillar, not the rest of the tip, was coated. The coated ferromagnetic film has a trough shape and a tapered end with a tip radius of -10 nm. The film is single domain because of the nanoscale size and shape anisotropy. Compared to conventional Ni wire tips, the new tips have a much smaller, magnetic cross section at the end of the tip, thus offering better imaging resolution and they have lower stray field, thus making them well suited to measuring soft magnetic materials.