Dormant chirality in magnetic two-dimensional materials.

It is well known that magnetic exchange interaction drives the behavior of magnetic materials, making them ferromagnetic (positive interaction, spins parallel) or antiferromagnetic (negative interaction, spins antiparallel). It is far less obvious that there exist components of exchange interaction that lead to chiral magnetism, i.e. causing the adjacent spins to assume orthogonal mutual ordering. Dzyaloshinskii-Moriya interaction (DMI) is one such interaction, first identified in the 60's, but it was only the recent observation of skyrmion lattices that instigated its further fundamental research and technological applications. DMI can only arise in systems that lack inversion symmetry and host strong spin-orbit coupling, a condition that is met in few bulk materials, and at interfaces of specifically designed magnetic heterostructures. In 2017, magnetic ordering was also observed in 2D materials, CrI3 being the first. There, magnetic atoms (Cr) are in direct bonding with non-magnetic atoms with strong spin-orbit coupling (I). Therefore DMI must be intrinsically present but is cancelled out in a perfect crystalline lattice so there is no apparent DMI, unless symmetry is broken (at the edges, defects, grain boundaries etc.). What are the microscopic mechanisms to awaken such a dormant DMI, how significant it can be, and how to tailor its release and the corresponding spin textures as a function of temperature and magnetic field, are the overarching themes in this project.

Keywords:MAGNETIC 2D MATERIALS

Disciplines:Magnetism and superconductivity, Nanophysics and nanosystems, Surfaces, interfaces, 2D materials, Phase transformations, Computational physics