Spintronics is a branch of electronics that aims to use the electron spin rather than its charge to transport and store information. The electron spin comes in two forms, "spin up" or "spin down," and would allow significantly more data to be stored and analyzed than is possible with current electronics. Moreover, spin computers would be able to process vast amounts of information while using less energy and generating much less heat than conventional computers.
Advances in spintronics have already impacted commercial products, enabling a huge increase in storage capacity of magnetic hard disks. However, the devices comprise ferromagnetic multilayers that act as spin filters and require conventional electrical charge currents in order to work. To garner the full potential of spintronics, further fundamental advances are urgently needed.
Researchers working in this field face a key challenge: how to generate and control spins without the simultaneous generation of electric current, and the resultant energy losses? This would enable not just data storage, but calculations to be realized directly using spin states.
As reported in the journal Science, Prof. Valenzuela and Dr. Costache have proposed and experimentally demonstrated a ratchet concept to control the spin motion. In analogy to a ratchet wrench, which provides uniform rotation from oscillatory motion, such ratchets achieve directed spin transport in one direction, in the presence of an oscillating signal. Most important, this signal could be an oscillatory current that results from environmental charge noise; thus future devices based on this concept could function by gathering energy from the environment.