Speaker

Prof. Yutaka Akagi / The University of Tokyo

Title

CP² triple-Q state in the SU(3) Kondo lattice model

Abstract

Recent years have seen significant interest in quantum condensates with SU(N) symmetry (N≥3), such as SU(N) Mott insulator (SU(N) magnets), within cold atom frameworks [1,2]. Advances have also been made in the experimental realization of Kondo physics, where itinerant electrons and localized spins interact, using two “orbital” degrees of freedom in alkaline earth metal fermions [3,4]. The feasibility offered by cold atom systems has intensified the focus on SU(N) Kondo lattice systems. So far, their magnetism has been clarified, mainly in one dimension [5].

Ferromagnetic Kondo coupling is a natural occurrence when considering Kondo lattice systems with cold atoms. For instance, in the SU(3) ferromagnetic Kondo lattice model, itinerant fermions with three colors align their magnetic dipoles and quadrupoles with SU(3) localized moments at each lattice site. In this work, we investigate the SU(3) ferromagnetic Kondo lattice model on a triangular lattice, extending methods from Refs. [6, 7] to map out the ground state phase diagram. We have identified that the smallest size CP² triple-Q state realizes [8], showcasing non-trivial topological magnetism with triple-Q peaks in both magnetic dipole and quadrupole structure factors [9]. Additional discovered phases include a CP² three-sublattice state and a CP² ferromagnetic state (refer to Ref. [5]). In this talk, we will discuss these phases in detail.

[1] S. Taie, R. Yamazaki, S. Sugawa, and Y. Takahashi, Nat. Phys. 8, 825 (2012).
[2] C. Hofrichter, L. Riegger, F. Scazza, M. Höfer, D. R. Fernandes, I. Bloch, and S. Fölling, Phys. Rev. X 6, 021030 (2016).
[3] L. Riegger, N. D. Oppong, M. Höfer, D. R. Fernandes, I. Bloch, and S. Fölling, Phys. Rev. Lett. 120, 143601 (2018).
[4] K. Ono, Y. Amano, T. Higomoto, Y. Saito, and Y. Takahashi., Phys. Rev. A 103, L041303 (2021).
[5] K. Totsuka, Phys. Rev. A 107, 033317 (2023).
[6] H. T. Ueda, Y. Akagi, and N. Shannon, Phys. Rev. A 93, 021606(R) (2016).
[7] K. Remund, R. Pohle, Y. Akagi, J. Romhányi, and N. Shannon, Phys. Rev. Research 4, 033106 (2022).
[8] See the classical-spin case: Y. Akagi and Y. Motome, J. Phys. Soc. Jpn. 79, 083711 (2010).
[9] See also CP² Skyrmion crystals in other systems: Y. Amari, Y. Akagi, S. B. Gudnason, M. Nitta, and Y. Shnir, Phys. Rev. B 106, L100406 (2022).

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Apr. 2005 – Mar. 2009: Bachelor Degree in Physics, Department of Physics, Tokyo Institute of Technology
Apr. 2009 – Mar. 2014: Ph.D. in Engineering, Department of Applied Physics, The University of Tokyo (Motome group)
Apr. 2014 – Oct. 2015: Postdoctoral Scholar, Theory of Quantum Matter Unit, OIST
Nov. 2015 – present: Assistant Professor, Katsura group, Department of Physics, The University of Tokyo
Oct. 2022 – present: PRESTO researcher, Japan Science and Technology Agency

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