Elucidating correlation-driven insulating state in an effective spin—½ antiferromagnet NdVO₄

The<i>J</i>_eff= ½ state: a result of interplay of strong electronic correlations (<i>U</i>) with spin-orbit coupling (SOC) and crystal field splitting, offers a platform in the research of quantum materials. In this context, 4<i>f</i>rare-earth based materials offer a fertile playground. Here, strong experimental and theoretical evidences for a<i>J</i>_eff= ½ state is established in a three-dimensional spin system NdVO₄. Magnetic measurements show the signatures of a SOC driven<i>J</i>_eff= ½ state along with the presence of antiferromagnetic (AFM) interaction between Nd³⁺moments, whereas, heat capacity reveals the presence of an AFM ordering around 0.8 K, within this state. An entropy of Rln2 (equivalent to<i>J</i>= ½) is released around 4 K which implies the presence of<i>J</i>_eff= ½ state at low temperatures. Total energy calculations within the density functional theory (DFT) framework reflect the central role of SOC in driving the Nd³⁺ions to host such a state with AFM correlations between them, which is in agreement with experimental results. Further, DFT + SOC calculations with and without the inclusion of<i>U</i>, points that electron-electron correlations give rise to the insulating state making NdVO₄a potential candidate for<i>U</i>-driven correlated Mott insulator.