Manufacturing Bits: Jan. 12

World’s smallest magnet; creep motion; expeditions in computing.


World’s smallest magnet
The University of Tokyo has developed what researchers claim is the world’s smallest nano-magnet.

The nano-size ferrite magnet consists of iron oxide. With the material, researches devised a 7.5nm structure with magnetic properties.

World's smallest magnet (Source: Shin-ichi Ohkoshi)

Charting the world’s smallest magnet (Source: Shin-ichi Ohkoshi)

Ferrite magnets are used in several applications, such as permanent magnets, magnetic recording media, electromagnetic wave absorbing materials and magnetic fluids. Nano-size magnets could be used in high-density magnetic recording for archive media.

Researchers from University of Tokyo have developed a method to synthesize epsilon-type iron oxide (ε-Fe2O3) particles. Ranging in sizes from 5nm to 40nm, the particles were first developed by using a precursor.

The precursor consisted of ferrihydrite nanoparticles, which were embedded in a SiO2 matrix. The precursor was sintered at 250 °C to 1295 °C for four hours in air, according to researchers.

This, in turn, formed iron oxide in a SiO2 matrix. The SiO2 matrix was then removed by chemical etching. “The ferrite magnet that we have developed may have applications as a future material for magnetic tape storage, a technology used by Google and others as a mass storage medium for archiving big data and the focus of intense interest,” said Shin-ichi Ohkoshi, a professor at the University of Tokyo, on the university’s Web site.

“Epsilon-type iron oxide has the lightest color among ferrite magnets, making it suitable for novel applications such as in transparent magnetic paints and magnetic color toner for printers,” Ohkoshi said.

Creep motion
Tohoku University has gained a new understanding of a phenomenon called creep motion.

Researchers examined the slow change of microscopic magnetic structures in metallic wires. The structure was induced by external driving forces, which is sometimes called creep motion.

This, in turn, allows research to understand how magnetic fields or electric currents act on a magnetic structure.

Schematic of domain wall creep. When a very weak magnetic field or electric current is applied to the magnetic wire with domain wall, the domain wall behaves as an elastic interface and slowly moves, creeps.  (Source: Tohoku University)

Schematic of domain wall creep. When a very weak magnetic field or electric current is applied to the magnetic wire with domain wall, the domain wall behaves as an elastic interface and slowly moves or creeps. (Source: Tohoku University)

Researchers from Tohoku University devised a wire device, which included a ferromagnetic metal (CoFeB). Then, they looked at the domain wall velocity for various magnitudes of a magnetic field. This was done while keeping the device temperature constant.

“Previous studies had shown that while the actions of magnetic fields and currents are the same for metallic materials, they are fundamentally different for semiconductor materials,” according to researchers from Tohoku. “The present study reveals that in cases where the sample satisfies a certain condition, the current acts on the magnetic structure in a different manner from the magnetic field case, irrespective of the intricacies of the material.”

Computer expeditions
The National Science Foundation (NSF) announced $30 million in funding for three “Expeditions in Computing” projects. Each grant will provide $10 million over five years.

The “Expeditions in Computing” program catalyzes far-reaching research. The first new project is called “The Science of Deep Specification.” This grant aims to eliminate software “bugs” that can lead to security vulnerabilities and computing errors by improving the formal methods–or the mathematically-based techniques–by which software is developed and verified.

The second project is called “Evolvable Living Computing — Understanding and Quantifying Synthetic Biological Systems’ Applicability, Performance, and Limits.” This grant will support efforts to create a systematic set of guidelines to measure and catalogue biological parts that can be used to engineer biological systems with predictable results. These guidelines will allow researchers to better understand what computing principles can be applied repeatedly and reliably to synthetic biology.

The third project is called “CompSustNet: Expanding the Horizons of Computational Sustainability.” Computational sustainability aims to apply computational techniques to balance environmental, economic and societal needs.

Initiated in 2008, the Expeditions program has funded 19 projects to date, with a total investment of approximately $190 million.

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