Stripe magnetic order in semimetallic triangular-lattice CeLi3Bi2

Magnetically frustrated triangular lattice materials are predicted to host exotic quantum states in the presence of conduction electrons. Yet, materials wherein the balance between short-range frustrated exchange interactions and long-range Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions can be fine tuned remain rare. Here, we present a comprehensive investigation of the triangular-lattice antiferromagnet CeLi3Bi2. Heat capacity, electrical resistivity, and nuclear magnetic resonance (NMR) indicate that CeLi3Bi2 is a low-carrier-density semimetal, in agreement with our band structure calculations. Further, NMR spin-lattice relaxation results reveal competing RKKY interactions and weak Kondo screening. Thermodynamic, magnetization, and neutron diffraction data are well described by an isolated ground-state Kramers doublet that orders antiferromagnetically at TN=1.28 K in a stripe structure, a strong indicator of magnetic frustration. Our combined findings place CeLi3Bi2 as a promising platform for tuning the interplay between geometric frustration and RKKY physics.