Candidate spin-liquid ground state in CsNdSe2 with an effective spin-1/2 triangular lattice

Abstract

Rare-earth-based triangular lattice materials are extremely attractive for studying unconventional magnetism. Here, we report the magnetic properties of layered CsNdSe2 based on direct current (DC) and alternating current (AC) susceptibility measurements down to 0.04 K. While the AC susceptibility at the zero DC field shows a broad hump below 0.5 K, there is no sign of any long-range magnetic ordering. Quantitative analysis of the DC magnetic susceptibility gives the negative Curie-Weiss (CW) temperature θCW < 0 in all directions, indicating antiferromagnetic interaction between Nd ions. Of particular interest is the low temperature magnetic susceptibility, which reflects the effective spin-1/2 state with θcwa/θcwc > 3. The estimated exchange interactions are Ja/kB= 1.42 K (in-plane) and Jc/kB= 0.44 K (out-of-plane), pointing to the anisotropic magnetism. First-principles calculations that include spin-orbit coupling and Coulomb correlations reveal multiple states with zero net magnetization for CsNdSe2. Both experiment and simulation strongly suggest CsNdSe2 has the spin liquid ground state with effective spin-1/2. Application of a magnetic field can induce long-range antiferromagnetic ordering with the maximum transition temperature around 0.3 K, in further support of the zero-field spin liquid state.