Seminar Paolo Barone "2D transition-metal halides: a playground for exotic magnetism"

The observation of long-range magnetic order in truly 2D materials has triggered a renewed interest in 2D magnetism. Van der Waals transition-metal dihalides and trihalides represent a wide class of promising materials that are prone to show exotic magnetic properties down to the two-dimensional limit. By combining ab-initio approaches based on Density Functional Theory and effective modeling, I will discuss the role played by geometric frustration and magnetic anisotropy in driving exotic phases, such as complex helimagnetism and topological spin lattices [1,2] as well as multiferroicity [3], in the class of Ni-based dihalides. These phases may develop even in the absence of the antisymmetric Dzyaloshinskii-Moriya exchange interaction, whereas magnetic anisotropy and frustration are strongly influenced by the atomic spin-orbit coupling of ligand atoms, as well as by the metal-ligand hybridization. Finally, I will present our recent results on curved magnetism in CrI3 monolayers, showing that relativistic effects are essential for an accurate description of flexomagnetic coupling parameters [4].

[1] D. Amoroso, P. Barone and S. Picozzi. "Spontaneous skyrmionic lattice from anisotropic symmetric exchange in a Ni-halide monolayer" Nature Communications 11, 5784 (2020)
[2] D. Amoroso, P. Barone, S. Picozzi. "Interplay between Single-Ion and Two-Ion Anisotropies in Frustrated 2D Semiconductors and Tuning of Magnetic Structures Topology" Nanomaterials 11, 1873 (2021)
[3] Q. Song, C. A. Occhialini, E. Ergeçen, B. Ilyas, D. Amoroso, P. Barone, J. Kapeghian, K. Watanabe, T. Taniguchi, A. S. Botana, S. Picozzi, N. Gedik, R. Comin. "Evidence for a single-layer van der Waals multiferroic", Nature 602, 601 (2022)
[4] A. Edström, D. Amoroso, S. Picozzi P. Barone, M. Stengel. "Curved magnetism in CrI3" Phys. Rev. Lett. 128, 177202 2022