A recent MIT study showed how new technology can be used to control and write magnetized bits in nano-structures, using voltage alone. This new technique also consumes much less power than using magnets or magnetism as well.
They envision a sort of nano-circuit, -wire or -racetrack with a series of transistor-like structures spaced at regular intervals above it. Nano-bits would be racing around these nano-wires as a series of magnetized domains. These new transitor-like devices would be a sort of onramp for the bits as well as stop-lights/speed limits for the racetrack.
Magnetic based racetrack memory issues
The problems with using magnets to write the bits in nano-racetrack is that magnetism casts a wide shadow and can impact adjacent race tracks, sort of like shingled writes (we last discussed in Shingled magnetic recording disks). The other problem has been a way to (magnetically) control the speed of racing bits so they can be isolated and read or written effectively.
Magneto-ionic racetrack memory solutions
But MIT researchers have discovered a way to use voltage to change the magnetic orientation of a bit on a race track. They also found a way through the use of voltage to precisely control the position of magnetic bits speeding around the track and to electronically isolate and select a bit.
What they have created is sort of a transistor for magnetized domains using ion-rich materials. Voltages can be used to attract or repel those ions and then those ions can interact with flowing magnetic domains to speed up or slow down the movement of magnetic domains.
Thus, the transistor-like device can be set to attract (or speed up) magnetized domains, slow down magnetized domains or stop them and also be used to change the magnetic orientation of a domain. MIT researchers call these devices Magneto-ionic devices.
Racetrack memory redefined
So now we have a way to (electronically) seek to bit data on a race track, a way to precisely (electronically) select bits on the race track, and a way to precisely (electronically) write data on a race track. And presumably, with an appropriate (magnetic) read head, a way to read this data. As an added bonus, apparently data once written on the racetrack requires no additional power to stay magnetized.
So the transistor-like devices are a combination of write heads, motors and brakes for the racetrack memory. Not sure, but if they can write, slow down and speedup magnetic domains, why can’t they read them as well that way the transistor-like devices could be a read head as well.
Why do they need more than one write-head per track. It seems to me that one should suffice for a fairly long track, not unlike disk drives. I suppose more of them would make the track faster to write. But they would all have to operate in tandem, speeding up or stoping the racing bits on the track all together and then starting them all back up, together again. Maybe this way they can write a byte or a word or a chunk of data all at the same time.
In any event, it seems that race track memory took a (literally) quantum leap forward with this new research out of MIT.
Racetrack memory futures
IBM has been talking about race track memory for some time now and this might be the last hurdle to overcome to getting there (we last discussed this in A “few exabytes-a-day” from SKA post).
In addition, there doesn’t appear to be any write cycle, bit duration or the need for erasing whole page issues with this type of technology. So as an underlying storage for a new sort of semi-conductor storage device (SSD) this has significant inherent advantages.
Not to mention that is all based on nano-based device sizes which means that it can pack a lot of bits in very little volume or area. So SSDs based on these racetrack memory technologies will be denser, faster, and require less energy – could you want.