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Frustrated magnetic systems have attracted significant attention recently as the possibility of realizing novel magnetic states such as spin liquid state [1]. K₂IrCl₆ is an exciting compound to study the ground-state selection and explore the magnetic phase diagram in a model antiferromagnet with face-centered-cubic frustration. In this talk, I will discuss our elastic and inelastic neutron scattering results which indicate the coexistence of a minority type-I phase with k=(100) and a previously revealed type-III phase with k=(1 ½ 0). This coexistence is also confirmed by the resonant elastic X-ray scattering measurement. Given that the type-III magnetic order is the dominant phase, the type-I magnetic order could be stabilized through local deviations from cubic symmetry, quantum order-by-disorder effect, or both [2,3]. This study will provide a sophisticated empirical basis for the understanding of ground-state selections by various mechanisms and for the possible materialization of quantum spin liquid in frustrated magnets.

[1] L. Balents, Nature 464, 199 (2010)

[2] A. Aczel et al, Phys. Rev. B 99, 134417 (2019)

[3] R. Schick,  arXiv:2206.12102 [cond-mat.str-el] (2022)