Speaker
Description
Engineering all magnetic phases within a single material platform would mark a significant milestone in materials science, simplifying device fabrication by eliminating the need for integrating different materials. We demonstrate that graphene can host all non-relativistic magnetic phases—diamagnetism, paramagnetism, ferromagnetism, antiferromagnetism, ferrimagnetism, altermagnetism and fully compensated ferrimagnetism —using single H atoms as building blocks. Their magnetic character is confirmed by density functional theory and mean-field Hubbard calculations. Notably, altermagnetism can be realized, exhibiting directionally spin-split bands coexisting with zero net magnetization due to spatial symmetries. Furthermore, fully compensated ferrimagnets can be created, lacking these symmetries and presenting unrestricted spin-splitting, with vanishing net magnetization protected by Lieb’s theorem. We take this idea to the laboratory and, through precise manipulation of H atoms by scanning tunneling microscopy, experimentally create unit cells of all magnetic phases. These findings open the door to the bottom-up design of magnetic phases via symmetry selection. We are currently extending our study with transport calculations on these systems, especially to check the polarization in Lieb compensated ferrimagnets and direction dependent polarization in altermagnets. We are also investigating spin-flip excitons on the antiferromagnets obtained from centrosymmetric arrangement of H atoms on graphene with our group’s code XATU, aiming to capture some of its magnonic properties.
References
[1] B. Viña-Bausá, M. A. García-Blázquez, S. Chourasia, R. Carrasco, D. Expósito, I. Brihuega, and J. J. Palacios, Building Unconventional Magnetic Phases on Graphene by H Atom Manipulation: From Altermagnets to Lieb Ferrimagnets, arXiv:2501.12329.
[2] A. J. Uría-Álvarez, J. J. Esteve-Paredes, M. A. García-Blázquez, and J. J. Palacios, Efficient computation of optical excitations in two-dimensional materials with the Xatu code, Computer Physics Communications 295, 109001 (2024).
