<< Tiny magnetic whirls that can occur in materials—so-called skyrmions— hold high promises for novel electronic devices or magnetic memory in which they are used as bits to store information. A fundamental prerequisite for any application is the stability of these magnetic whirls. >>
<< Previously, a standard model of the relevant magnetic interactions contributing to the (energy) barrier has been established. >>
<< one type of magnetic interactions has so far been overlooked. In the 1920s Werner Heisenberg could explain the occurrence of ferromagnetism by the quantum mechanical exchange interaction which results from the spin dependent "hopping" of electrons between two atoms. "If one considers the electron hopping between more atoms, higher-order exchange interactions occur," says Dr. Souvik Paul, (..). However, these interactions are much weaker than the pair-wise exchange proposed by Heisenberg and were thus neglected in the research on skyrmions. >>
<< Based on atomistic simulations and quantum mechanical calculations (..) (AA) have now explained that these weak interactions (at a higher temperature than room temperature) can still provide a surprisingly large contribution to skyrmion stability. Especially the cyclic hopping over four atomic sites (..) influences the energy of the transition state extraordinarily strongly (..), where only a few atomic bar magnets are tilted against each other. Even stable antiskyrmions were found in the simulations which are advantageous for some future data storage concepts but typically decay too fast. >>
Julia Siekmann. Scientists find a new mechanism for the stabilization of skyrmions. Kiel University. Sep 21, 2020.
Paul, S., Haldar, S., von Malottki, S. et al. Role of higher- order exchange interactions for skyrmion stability. Nat Commun 11, 4756. doi: 10.1038/ s41467-020-18473-x. Sep 21, 2020.
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