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MA: Fachverband Magnetismus

MA 14: Surface Magnetism

MA 14.5: Talk

Tuesday, March 28, 2023, 11:00–11:15, HSZ 04

Conical spin-spirals at a ferromagnet’s surface: a theoretical analysis — •Gustav Bihlmayer¹, Patrick Härtl², Markus Leisegang², Matthias Bode², and Stefan Blügel¹ — ¹Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich, Germany — ²Universität Würzburg, Germany

The properties of surface layers of a magnetic material can differ substantially from those of the bulk material. A prominent example is the Dzyaloshinskii-Moriya interaction (DMI), resulting from inversion-symmetry breaking at the surface, but also the magnetic anisotropy and the exchange interactions are locally modified. Gd(0001) is here a well-investigated model surface but despite its sensitivity of exchange interactions to the local environment, experimental data indicated that it behaves as homogeneous Heisenberg system [1]. Recent observations of spin-spirals at the surface of epitaxial Gd(0001) with spin-polarized scanning tunneling microscopy let us re-investigate this system. Density functional theory (DFT) calculations show that not only a sizable DMI can be found at the Gd(0001) surface but also the exchange interactions are modified to drive the system locally towards a conical spin-spiral state. Since the magnetic anisotropy and the exchange interactions with the ferromagnetic bulk material disfavor non-collinear magnetic states, only slight modifications of the exchange interactions make these spirals visible. We explore the phase diagram numerically and with the help of atomistic spin-dynamics simulations.

[1] C. S. Arnold and D. P. Pappas, Phys. Rev. Lett. 85, 5202 (2000)