Chemical Pressure Tuning Magnetism from Pyrochlore to Triangular Lattices.

Geometrically frustrated lattices combined with magnetism usually host quantum fluctuations that suppress magnetic orders and generate highly entangled ground states. Three-dimensionally (3D) frustrated magnets generally exist in the diamond and pyrochlore lattices, while two-dimensionally (2D) frustrated geometries contain Kagomé, triangular, and honeycomb lattices. In this work, we reported using chemical pressure to tune the magnetism of the pyrochlore lattice in LiYbSe 2 into a triangular lattice by doping Ga or In. Li 3- x Ga x Yb 3 Se 6 and Li 3- x In x Yb 3- y In y Se 6 /Li 3- x In x Yb 3- y □ y Se 6 crystallize in a trigonal α-NaFeO 2 structure-type (space group R 3̅ m ) and can be synthesized using either LiCl or Se flux. In Li 3- x Ga x Yb 3 Se 6 , Ga 3+ and Li + are mixed, leaving Yb 3+ on the triangular plane. Instead of just Li + being replaced in Li 3- x Ga x Yb 3 Se 6 , In 3+ was observed in both the Li + and Yb 3+ layers in Li 3- x In x Yb 3- y In y Se 6 depending on the reaction conditions. Dominant antiferromagnetic interactions are revealed by magnetic measurements in both Li 3- x Ga x Yb 3 Se 6 and Li 3- x In x Yb 3- y In y Se 6 /Li 3- x In x Yb 3- y □ y Se 6 . However, no long-range magnetic order is detected in thermomagnetic measurements above 1.8 K due to geometrical frustration. Thus, Li 3- x Ga x Yb 3 Se 6 , Li 3- x In x Yb 3- y In y Se 6 /Li 3- x In x Yb 3- y □ y Se 6 , and the LiYbSe 2 previously discovered by our group provide an ideal platform to understand the complex structure-magnetism correlations from 3D to 2D frustrated lattices.