AUSTRIA.VIENNA: A computer’s initial state can be restored by switching a bit in its memory, then switching it back.”0 and 1″ refers to only two possible states.
Astonishingly, a crystal made of gadolinium and manganese oxides has now been found at TU Wien (Vienna), and it contains an atomic switch that must be turned back and forth not just once, but twice, before returning to the original form. The gadolinium atoms’ spin completes one complete rotation during this dual switching-on and switching-off procedure. This is comparable to a crankshaft, which transforms an up-and-down movement into a circular movement.
Fascinating opportunities in material physics are made possible by this novel occurrence. With such devices, even information may be stored. A description of the peculiar atomic transition has just been published in the academic journal Nature.
Electrical and Magnetic characteristics are correlated
The electrical and magnetic characteristics of materials are typically distinguished. The movement of charge carriers, such as electrons through metal or ions with altered positions, provides the basis for electrical properties.
The spin of atoms, on the other hand, which is the particle’s intrinsic angular momentum and can point in a very precise direction, much like the Earth’s axis of rotation, is strongly tied to magnetic properties.
There are some materials, though, where magnetic and electrical processes are very strongly related. Such materials are being studied by Prof. Andrei Pimenov and his group at the Institute of Solid State Physics at TU Wien. “We examined how its electrical polarisation altered upon exposure to a magnetic field of a particular substance made of gadolinium, manganese, and oxygen,” says Andrei Pimenov. “We were interested in examining how magnetism can affect a material’s electrical properties. And to our surprise, we discovered an unexpected behaviour,” he added.
At the beginning
The material is initially electrically polarised, with one side positively and the other negatively charged. The polarisation barely changes when a powerful magnetic field is turned on after that. The polarisation suddenly reverses: the side that was positively charged before is now negatively charged, and vice versa, if the magnetic field is then turned off once more. This is a dramatic change.
You can now repeat the procedure a second time: If you activate the magnetic field once more, the electric polarisation will essentially remain constant. The polarisation reverses after the magnetic field is turned off, going back to its initial state.
“This is very amazing,” declares Andrei Pimenov. We go through four different steps, during which the material’s internal properties change each time. However, the polarisation only changes twice, so the initial state is only reached after the fourth step.
Four-stroke resemblance for gadolinium
A closer inspection reveals that the gadolinium atoms are the cause of this behaviour since they each undergo a 90-degree change in spin direction throughout each of the four phases. According to Andrei Pimenov, “it’s kind of like a four-stroke engine for atoms.” “A four-stroke engine also requires four steps to return to the initial state, during which the cylinder moves twice up and down. In our scenario, the magnetic field oscillates twice before returning to its previous position and the gadolinium atoms spin once more pointing in the original direction.”
A system with four alternative states would have a storage capacity of two bits per switch, instead of the typical one bit of information for “0” or “1,” which is theoretically possible to do with such materials.
However, the phenomenon is also very intriguing for sensor technology, as one might use it to create a magnetic pulse counter, for instance. It is another example of a so-called “topological effect,” a class of material phenomena that has attracted significant attention in solid-state physics for years and should facilitate the development of novel materials.
The phenomenon offers significant new inputs for theoretical research.
Also Read: The Most Detailed Images Of Individual Atoms Captured At Cornell University
