MSE Seminar: “Spirals and skyrmions in magnets and their emergent electromagnetism”

Spirals and skyrmion textures are complex magnetic states in solids which, through coupling to the Fermi sea, may generate fascinating non-dissipative electromagnetic responses. A unified description is currently being developed through the concept of quantum-mechanical Berry curvature, in this case corresponding to an emergent magnetic field Ωk living in reciprocal space (k-space).

Based on extensive material search we synthesized large single crystals of a variety of intermetallics and oxides. A new, centrosymmetric family of rare earth intermetallics with spirals and skyrmion spin-vortices of very short characteristic length scale (<5 nanometers) was identified using transport and resonant elastic x-ray scattering experiments [1,2].

In the model compound Gd2PdSi3, Ωk is shown to arise from a combination of canted spin texture and band degeneracies in k-space [3]. Moreover, spin-dynamics induced by an applied AC current in the related Gd3Ru4Al12 generate a phase-shifted voltage. This emergent inductance grows as the lateral dimensions of the sample become smaller and smaller – contrary to the case of, e.g., a classical coil-based inductor [4].