Probing Effective Spin 1/2 Crystal Field Dynamics in a magnetic insulator NdVO4 via Inelastic Neutron Scattering

Three -dimensional spin systems with strong interplay of spin-orbit coupling and non-cubic crystal electric field (CEF) leads to an effective spin Jeff – ½ ground state at low temperatures which offers a platform to realize novel quantum spin liquid (QSL) state and Mott insulating state in case of comparable on-site coulombic interaction (U). In the context of Jeff – ½ magnetic ground state, a rare-earth orthovanadate, NdVO4 is a potential candidate as revealed by basic thermodynamic measurements. Along with this, density functional theory (DFT) studies show the opening of a band gap on inclusion of U, hinting towards Mott-insulating state. Since in NdVO4, Nd3+ has total angular momentum (J) = 9/2 and this ten-fold degenerate state is split into five Kramer doublets by the D2d crystal field. By doing the Inelastic Neutron Scattering (INS) measurements, we want to probe the CEF spectra and directly visualize the magnetic excitations corresponding to the ground state and excited states. By evaluating the integrated intensity as a function of energy at a particular temperature, we wish to find the intensity and position of the excitations. Further, we also want to do simultaneous fit to INS spectra at various temperatures together with the magnetic susceptibility and heat capacity data to obtain the unique set of CEF parameters.