![]() ![]() This new study shows that in addition to the global movement of skyrmions across a material, the local behavior of individual skyrmions can also be useful. Because they're so robust, researchers are interested in using their movement to perform computations and to store data. And once they're formed, they're very difficult to get rid of. Skyrmions, which are generally about 1 micrometer (a millionth of a meter) or smaller in diameter, behave a bit like a kind of particle, zipping across the material from side to side. When that happens, the spins of surrounding electrons are perturbed to some extent, forming a magnetic whirlpool surrounding the flipped electron-a skyrmion. When these materials are excited with electricity or a magnetic field, some of the electron spins flip as the energy of the system rises. Some two-dimensional materials, in their lowest energy states, have a property called perpendicular magnetic anisotropy-meaning the spins of electrons all point in a direction perpendicular to the film. ![]() Spin can be thought of as the tiny magnetic moment of each electron, which points up, down or somewhere in between. Skyrmions arise from the "spin" of electrons in ultra-thin materials. This new study adds skyrmions to the list of true random number generators. Other techniques harness the inherent randomness in quantum mechanics-the behavior of particles at the tiniest scale. Random fluctuations in electrical current flowing through a resistor, for example, can be used to generate random numbers. Methods of producing true random numbers often draw on the natural world. While pseudorandom numbers are sufficient in many settings, applications like data security-which uses numbers that can't be guessed by an outside party-require true random numbers. With enough information about the algorithm or its output, it could be possible for someone to find patterns in the numbers that the algorithm produces. But because the algorithm used to generate the number is deterministic, the numbers aren't truly random. Computers use an algorithm to generate random numbers based on an initial starting place, a seed number. Most random numbers produced by computers aren't random in the strictest sense. In this case, we show that we can use those fluctuations to generate random numbers, potentially as many as 10 million digits per second." "But in this work, we show that purely random fluctuations in the size of skyrmions can be useful as well. "There has been a lot of research into the global dynamics of skyrmions, using their movements as a basis for performing computations," said Gang Xiao, chair of the Department of Physics at Brown and senior author of the research. Discovered around a half-decade ago, skyrmions have sparked interest in physics as a path toward next-generation computing devices that take advantage of the magnetic properties of particles-a field known as spintronics. Their research, published in Nature Communications, reveals previously unexplored dynamics of single skyrmions, the researchers say. ![]()
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