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EPFL scientists have produced controllable stable skyrmions using laser pulses, taking a step towards significantly more energy-efficient memory devices. The work is published in Physical Review Letters.
A skyrmion is a collection of electron spins that look like a vortex in certain magnetic materials. Skyrmions can exist individually or in patterns referred to as lattices. Named after British physicist Tony Skyrme who first theorized the existence of their elementary-particle counterparts in 1962, skyrmions have attracted attention for their potential in being used in so-called "spintronic" devices, which would use the spin rather than the charge of electrons, thus becoming significantly more miniaturized and energy-efficient.
Interest - Memory-storage - Technologies - Skyrmions - Energy
Most interest has been focused on memory-storage technologies. Skyrmions can be rather stable and require very little energy for writing or erasing them: some studies have shown that creating and annihilating skyrmions could be almost 10,000 times more energy-efficient than conventional data-storage devices. However, this would require a fast and reliable way of controlling and manipulating individual skyrmions.
Now, the labs of Fabrizio Carbone and Henrik M. Rønnow at EPFL have been able to write and erase stable skyrmions using laser pulses. The scientists used an iron-germanium alloy, which can host skyrmions at around 0oC, not too far from room temperature. This is important in of itself, as many of these fundamental experiments usually take place at temperatures too low to ever be commercially meaningful.
Researchers - Advantage - Effect - Temperature - Jump
The researchers took advantage of the super-cooling effect that follows an ultrafast temperature jump, which is itself induced in the alloy by an ultrashort laser pulse. During the super-cooling, skyrmions can be frozen-in in places where they would not occur in conventional equilibrium conditions.
The forming skyrmions were imaged by using time-resolved cryogenic Lorentz electron microscopy, which can "see" magnetic domain structures and magnetization reversal mechanisms in real space and...
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