Physics Spring 2024 Colloquium: Emergent phases in quantum magnets: fractionalization, fragmenta- tion and new particles

Abstract: Moire superlattices of van der Waals materials have surfaced as new tunable quantum platforms for the realization of emergent phases. While moire-induced
electronic phases have been extensively explored over the past few years, moire engineering of magnetic phases is a newer emerging topic. In the  rst part of my talk, I will discuss how stacking dependent interlayer exchange can be used to create novel spin textures such as skyrmions. I will illustrate this mechanism by applying it to twisted bilayers of Cr-based trihalides (1) and  -RuCl3 (2). In the second part, I will focus on quantum spin liquid bilayers and discuss how twist angle and interlayer exchange can be utilized to create new topological phases with new emergent quasiparticles such as `fractionalized Goldstone bosons' in these systems (3,4,5).

(1) M. Akram, H. LaBollita, D. Dey, J. Kapeghian, O. Erten, A. Botana Nano
Lett. 15, 6633 (2021).
(2) M. Akram, J. Kapeghian, J. Das, R. Valenti, A. Botana, O. Erten Nano
Lett. 24, 890 (2024).
(3) E. Nica, M. Akram, A. Vijayvargia, R. Moessner, O. Erten npj Quantum
Materials 8, 9 (2023).
(4) A. Vijayvargia, E. Nica, R. Moessner, Y.-M. Lu, O. Erten Phys. Rev.
Research 5, L022062 (2023).
(5) A. Vijayvargia, U. Seifert, O. Erten Phys. Rev. B 109, 024439 (2024).
1

Bio: Onur Erten obtained his doctorate at The Ohio State University in 2013 and has worked at Rutgers University and Max Planck Institute for the Physics of Complex Systems before joining Arizona State University as an assistant professor. His research interests lie in the field of theoretical condensed matter physics: strongly correlated electron systems, quantum magnetism, superconductivity and topological phases in quantum materials.

In-person only. Refreshments at 2:30pm, PAS