부산대학교 도서관

The interplay between competing degrees of freedom can stabilize non-trivial magnetic states in correlated electron materials. Frustration-induced strong quantum fluctuations can evade long-range magnetic ordering leading to exotic quantum states such as spin liquids in two-dimensional spin-lattices such as triangular and kagome structures. However, the experimental realization of dynamic and correlated quantum states is rare in three-dimensional (3D) frustrated magnets wherein quantum fluctuations are less prominent. Herein, we report the crystal structure, magnetic susceptibility, electron spin resonance (ESR) and specific heat studies accompanied by crystal electric field (CEF) calculations on a 3D frustrated magnet Yb3Sc2Ga3O12. In this material, Yb3+ ions form a three-dimensional network of corner-sharing triangles known as hyperkagome lattice without any detectable anti-site disorder. Our results reveal a low energy state with Jeff = 1/2 degrees of freedom in the Kramers doublet state. The zero field-cooled and field cooled magnetic susceptibility taken in 0.001 T rules out the presence of spin-freezing down to 1.8K. The Curie-Weiss (CW) fit to low-T susceptibility data yields a small and negative CW temperature indicating the presence of a weak antiferromagnetic interaction between Jeff = 1/2 (Yb3+) moments. The Yb-ESR displays a broad line of non-Lorentzian shape that suggests considerable magnetic anisotropy in Yb3Sc2Ga3O12. The CEF calculations suggest that the ground state is well separated from the excited states, which are in good agreement with experimental results. The absence of long-range magnetic ordering indicates a dynamic liquid-like ground state at least down to 130 mK. Furthermore, zero field specific heat shows a broad maximum around 200 mK suggesting the presence of short-range spin correlations in this 3D frustrated antiferromagnet.