Machine Design

Nanoring memory

Magnetic randomaccess-memory (MRAM) could make it possible to store 100 movies on a coin-sized chip, even when it (the chip) is powered down.

Symmetrical nanorings & Asymmetrical nanorings

MRAM would also be much faster than conventional solid-state memories yet consume 99% less energy.

The challenge, to date, has been finding a fast, reliable, and inexpensive way to build stable and densely packed magnetic memory cells. Now, a team of researchers at The Johns Hopkins University may have an answer: tiny, irregularly shaped cobalt or nickel "nanorings." An asymmetrical design lets more of the nanorings reach a so-called "vortex state," meaning that they produce no magnetic stray fields. The property lets them tightly pack together without interfering with one another, boosting storage density.

A multistep process involving self-assembly, thin-film deposition and dry etching makes the nanorings. Etching the rings with an argon-ion beam at the end of the process, and tilting the substrate on which the rings are formed, gives them their special properties. Researchers say 100-nm symmetric nanorings have roughly a 40% chance of reaching the desired vortex state, while asymmetric nanorings have between a 40 and 100% chance. Funding for the research comes from the National Science Foundation.

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