Fig. 5: Magnetic states of NiI2.

Phase diagram encompassing all the magnetic states (HL1, HL2, HL3, HL4, and AFM, as described in Fig. S9) with differing intralayer and interlayer exchange interactions. HL2 is identified as the helimagnetic ground state for NiI2 at low temperature. The red data points represent the exchange interaction under pressure, sourced from DFT calculations in ref. 38.