Read an article today in ScienceDaily on [a] New way to write magnetic info … that discusses research done at Imperial College Of London that used a magnetic force microscope (small magnetic probe) to write magnetic fields onto a dense array of nanowires.
Frustrated metamaterials needed
The original research is written up in a Nature article Realization of ground state in artificial kagome spin ice via topological defect driven magnetic writing (paywall). Unclear what that means but the paper abstract discusses geometrically frustrated magnetic metamaterials. This is where the physical size or geometrical properties of the materials at the nanometer scale restricts or limits the magnetic states that material can exhibit.
Magnetic storage deals with magnetic material but there are a number of unique interactions of magnetic material when in close (nm) proximity to one another and the way nanowire geometrically frustrated magnetic metamaterials can be magnetized to different magnetic moments which can be exploited for other uses. These interactions and magnetic moments can be combined to provide electronic circuitry and data storage.
I believe the research provides a proof point that such materials can be written, in close proximity to one another using a magnetic force microscope.
Why it’s important
The key is the potential to create magnonic circuitry based on the pattern of moments writen into an array of nanowires. In doing so, one can fabricate any electrical circuit. It’s almost like photolithography but without fabs, chemicals, or laser scanners.
At first I thought this could be a denser storage device, but the potential is much greater if electronic circuitry could be constructed without having to fabricate semiconductors. It would seem ideal for testing out circuitry before manufacturing. And ultimately if it could be scaled up, the manufacture/fabrication of electronic circuitry itself could be done using these techniques.
Speed, endurance, write limits?
There was no information in the public article about the speed of writing the “frustrated magnetic metamaterials”. But an atomic force microscope can scan 150×150 micrometers in several minutes. If we assume that a typical chip size today is 150×150 mm, then this would take 1E6 times several minutes, or ~2K days. With multiple scanning force microscopes operating concurrently we could cut this down by a factor of 10 or 100 and maybe someday 1000. 2 days to write any electronic circuit on the order of todays 23nm devices with nanowires and magnetic force microscopes would be a significant advance
Also there was no mention of endurance, write limits or other characteristics we have learned to love with Flash storage. But the assumption is that it can be written multiple times and that the pattern stays around for some amount of time.
How magnetics generate electronic circuits
Neither Wikipedia page, the public article or the paywall articles’ abstract describes how Magnonics can supply electronic circuitry. However both the abstract and the public article discuss applications for this new technology in hardware based neural networks using arrays of densely packed nanowires.
Presumably, by writing different magnetic patterns in these nanowire metamaterials, such patterns can be used to simulate hardware connected neurons. This means that the magnetic information can be overwritten because it can be trained. Also, such magnetic circuits can be constructed to: a) can create different path for electrons to flow through the material; b) can restrict or enhance this electronic flow, and c) can integrate across a number of inputs and determine how electronic flow will proceed from a simulated neuron.
If magnonics can do all that, it’s very similar to electronic gates today in CPU, GPUs and other electronic circuitry. Maybe it cannot simulate every gate or electronic device that’s found in todays CPUs but it’s a step in the right direction. And magnonics is relatively new. Silicon transistors are over 70 years old and the integrated circuit is almost 60 years old. So in time, magnonics could very well become the next generation of chip technology.
Writing speed is a problem. Maybe if they spun the nanowire array around the magnetic force microscope…
Photo Credits: Real space observation of emergent magnetic monopoles … Nature article;
Realization of ground state in artificial kagome spin ice via topological defect driven magnetic writing, Nature article