Dresden 2017 – wissenschaftliches Programm
MA 44.2: Vortrag
Mittwoch, 22. März 2017, 15:15–15:30, HSZ 403
Quasi-toroidal poling of a nanomagnetic lattice — •Jannis Lehmann1, Claire Donnelly1,2, Peter Derlet2, Laura Heyderman1,2, and Manfred Fiebig1 — 1Department of Materials, ETH Zurich, Switzerland — 2Paul Scherrer Institute, Villigen PSI, Switzerland
Two-dimensional dipolar coupled magnetic nanostructures can be seen as model spin systems to investigate phenomena such as spontaneous order or magnetic frustration. It is thus possible to model specific types of ferroic order artificially by implementing design elements at the mesoscale. In a suitably engineered unit cell it is possible to achieve uniform spin-ordering in the form of magnetic whirls defining a net toroidal moment. Considering the lattice as a whole, the system can then form energetically degenerate toroidal domains in its ground state with opposite chirality. Our unit cell consists of four lithographically patterned sub-micrometer permalloy bars that are arranged on a silicon substrate forming the edges of a square. We present a strongly coupled nanomagnetic lattice that forms toroidal domains in its as-grown state. A saturated magnetized non-toroidal state can then be switched to a toroidal state by using the stray field of a magnetic tip in a scanning probe microscope. We interpret the poling procedure in terms of application of an effective toroidal field and present the possibility to write domains of defined handedness. As a first quasi-toroidal poling process in an artificial lattice, this work is an important step towards accessing the physics of ferrotoroidicity as a new type of ferroic order at mesoscopic length scales.