Special Seminar
Name: Prof. Je-Geun Park
Affiliation: Department of Physics & Astronomy, Seoul National University
Title: Kitaev physics on two-dimensional materials
Date & Time: Friday, 31stJanuary 2025 at 11:00 a.m.
Venue: Rajarshi Bhattacharya Memorial Lecture Hall, Chemical Sciences Building
Abstract:
It is rare to encounter a model whose solution can be obtained analytically. The Kitaev model, also known as the quantum compass model, stands out as a recent and exceptional example with intriguing implications, such as the emergence of fractionalized Majorana fermions [1]. Khaliullin and collaborators first suggested that the Kitaev model could be realized in specific oxides with 90° bond angles [2]. Since then, there has been a surge of interest in experimentally realizing the Kitaev model, with α-RuCl₃ emerging as a prominent example [3,4].Kitaev physics necessitates two key ingredients: the Hilbert space of a J-manifold and strong spin-orbit coupling. In principle, these criteria can be satisfied in several materials.
In this talk, I will introduce two such examples of van der Waals magnets: CoI₂ [5] and NiI₂ [6]. Intriguingly, both systems are multiferroic, exhibiting a coexistence of antiferromagnetism and ferroelectricity. Using inelastic neutron scattering, we have explored their spin dynamics and analyzed the data with several theoretical models. Our findings confirm that both systems host significant Kitaev interactions, highlighting their potential as platforms for studying exotic quantum phenomena.
References:
[1]A.Kitaev, Annals of Physics321, 2-111 (2006)
[2]G. Jackeli and G. Khaliullin. Phys. Rev. Lett. 102, 017205 (2009)
[3]A. Banerjee, et al., Science356, 1055-1059 (2017)
[4] S. Do, et al., Nature Physics 13,1079–1084 (2017)
[5]C. Kim, et al., Nature Physics 19, 1624–1629 (2023)
[6] C. Kim, et al., (submitted)