Special Interdisciplinary QC-CM Seminar | What are altermagnets and why are they special?

Altermagnetic materials are characterized by collinear magnetic order with a vanishing net magnetic moment, but nevertheless have a spin-splitting in their non-relativistic electronic band structure. From ab initio calculations we have identified around 60 altermagnetic materials. From a theoretical point of view several physical properties that render altermagnets different from canonical antiferro-, ferro- and ferri-magnets will be discussed. These include certain spin and heat transport features and piezomagnetic responses. By symmetry in principle also an anomalous Hall effect (AHE) may be allowed and we introduce an altermagnetic model in which the emergence of an AHE is driven by interactions. Quantum Monte Carlo simulations show that the system undergoes a finite temperature phase transition governed by a primary antiferromagnetic order parameter accompanied by a secondary altermagnetic one. The emergence of both orders turns the metallic state of the system, away from half-filling, into an altermagnet with zero net moment but finite AHE.

References:
— Y. Guo, H. Liu, O. Janson, I.C. Fulga, J. van den Brink, and J.I. Facio, Spin-split collinear antiferromagnets: A large-scale ab-initio study, Materials Today Physics, 32, 100991 (2023)
— T. Sato, S. Haddad, I.C. Fulga, F.F. Assaad, and J. van den Brink, Altermagnetic anomalous Hall effect emerging from electronic correlations, Phys. Rev. Lett. 133, 086503 (2024)
— O. Gomonay, V. P. Kravchuk, R. Jaeschke-Ubiergo, K. V. Yershov, T. Jungwirth, L. Šmejkal, J. van den Brink, J. Sinova, Structure, control, and dynamics of altermagnetic textures, npj Spintronics 2, 35 (2024)
— C. Li, M. Hu, Z. Li, Y. Wang, W. Chen, B. Thiagarajan, M. Leandersson, C. Polley, T. Kim, H. Liu, C. Fulga, M.G. Vergniory, O. Janson, O. Tjernberg, and J. van den Brink, Topological Weyl Altermagnetism in CrSb, arXiv:2405.14777 (2024)

Jeroen van den Brink is a Dutch theoretical condensed matter physicist renowned for his contributions to the understanding of strongly correlated quantum materials. Since 2009, he has served as the Director of the Institute for Theoretical Solid State Physics at the Leibniz Institute for Solid State and Materials Research (IFW) in Dresden, Germany. He also holds a professorship in solid-state theory at the Dresden University of Technology.

Van den Brink earned his PhD from the University of Groningen and was a professor of theoretical condensed matter physics, working at Leiden University and Radboud University Nijmegen, The Netherlands. In 2009, he was a visiting professor at the Stanford Institute for Materials and Energy Science.

His research focuses on theoretical condensed matter physics, particularly electronic structure theory, correlated electron systems, topological states of matter, and the theory of quantum matter. His work has earned him several accolades, including the Humboldt Research Prize in 2018 and the Van der Waals Professorial Chair at the University of Amsterdam in 2020.