This talk was part of the Workshop on "Spin-Orbit Entangled Quantum Magnetism" held at the ESI September 23 -- 27, 2024.

Two-dimensional Nb3Cl8 has been proposed as a promising multiferroic material exhibiting ferrovalley coupling and switchanble ferroelectric ground state. Here we show that such ferrovalley coupling is strongly dependent on the magnetic ground state and is absent in the helimagneti state that is predicted to have the lowest energy in DFT. Moreover, it is shown that switching the polar ground state by an external electric field is dubious due to a complicated polarization profile along the switching path. On the other hand, the compoiund is shown to exhibit a rich phase diagram and undergoes a first order magnteic phase transition (from commensurate non-collinear to long-range spin spiral) when subjected to strong electric fields.