SFB 767 - TP C10 Control of magnetic nanostructures by spin currents and thermal gradients

  • SFB 767 Kontrollierte Nanosysteme
  • FB Physik
    Rózsa, Levente; Palotás, Krisztián; Deák, András; Simon, Eszter; Yanes, Rocio; Udvardi, László; Szunyogh, László; Nowak, Ulrich (2017): Formation and stability of metastable skyrmionic spin structures with various topologies in an ultrathin film Physical Review B ; 95 (2017), 9. - 094423. - ISSN 2469-9950. - eISSN 2469-9969

Formation and stability of metastable skyrmionic spin structures with various topologies in an ultrathin film

We observe metastable localized spin configurations with topological charges ranging from Q=-3 to Q=2 in a (Pt<sub>0.95</sub>Ir<sub>0.05</sub>)/Fe bilayer on Pd(111) surface by performing spin dynamics simulations, using a classical Hamiltonian parametrized by ab initio calculations. We demonstrate that the frustration of the isotropic exchange interactions is responsible for the creation of these various types of skyrmionic structures. The Dzyaloshinsky--Moriya interaction present due to the breaking of inversion symmetry at the surface energetically favors skyrmions with Q=-1, distorts the shape of the other objects, and defines a preferred orientation for them with respect to the underlying lattice.

Origin (projects)

    Schirm, Christian; Matt, Manuel; Pauly, Fabian; Cuevas, Juan Carlos; Nielaba, Peter; Scheer, Elke (2013): A current-driven single-atom memory Nature Nanotechnology ; 8 (2013), 9. - S. 645-648. - ISSN 1748-3387. - eISSN 1748-3395

A current-driven single-atom memory

The possibility of fabricating electronic devices with functional building blocks of atomic size is a major driving force of nanotechnology. The key elements in electronic circuits are switches, usually realized by transistors, which can be configured to perform memory operations. Electronic switches have been miniaturized all the way down to the atomic scale. However, at such scales, three-terminal devices are technically challenging to implement. Here we show that a metallic atomic-scale contact can be operated as a reliable and fatigue- resistant two-terminal switch. We apply a careful electromigration protocol to toggle the conductance of an aluminium atomic contact between two well-defined values in the range of a few conductance quanta. Using the nonlinearities of the current–voltage characteristics caused by superconductivity in combination with molecular dynamics and quantum transport calculations, we provide evidence that the switching process is caused by the reversible rearrangement of single atoms. Owing to its hysteretic behaviour with two distinct states, this two-terminal switch can be used as a non-volatile information storage element.

Origin (projects)

Funding sources
Name Project no. Description Period
SFB826/1101.01.2012 – 31.12.2019
Further information
Period: 01.01.2012 – 31.12.2019