Non-coplanar helimagnetism in the layered van-der-Waals metal DyTe3

Abstract

Magnetic materials with highly anisotropic chemical bonding can be exfoliated to realize ultrathin sheets or interfaces with highly controllable optical or spintronics responses, while also promising novel cross-correlation phenomena between electric polarization and the magnetic texture. The vast majority of these van-der-Waals magnets are collinear ferro-, ferri-, or antiferromagnets, with a particular scarcity of lattice-incommensurate helimagnets of defined left- or right-handed rotation sense, or helicity. Here we use polarized neutron scattering to reveal cycloidal, or conical, magnetic structures in DyTe3, where insulating double-slabs of dysprosium square nets are separated by highly metallic tellurium layers. We identify a hierarchy of energy scales with - in order of decreasing strength - antiferromagnetic exchange interactions, magnetocrystalline anisotropy, and periodic modulations of the exchange energy. The latter are attributed to magneto-elastic coupling to the unconventional charge order in DyTe3. This easily cleavable metallic helimagnet also hosts a complex magnetic phase diagram indicative of competing interactions. Our work paves the way for twistronics research, where helimagnetic layers can be combined to form complex spin textures on-demand, using the vast family of rare earth chalcogenides and beyond.

Designing giant Hall response in layered topological semimetals

“…Our materials could on their own serve as a platform for further study: one avenue would perhaps be seeing how mixing of dysprosium and terbium, and thus the spin state, can be used to control the magnetism. Also interesting is comparison to tellurides and antimonides with related structures: the tellurides have been reported by us and others to produce complex magnetism and topological states [45][46][47][48], however no clear Hall effect anomaly has been observed in any of them. We can conjecture that the mixed square-net layer that provides the second environment for the lanthanides is the critical -and missing -element, however further study will likely provide a more complete answer.…”