We present a detailed investigation of the magnetic properties of the spin-3 2 system Li 2 Co(WO 4 ) 2 by means of magnetic susceptibility and specific heat. Our experimental results show that in Li 2 Co(WO 4 ) 2 short-range antiferromagnetic (AFM) correlations appear near χ max ∼ 11 K and two successive long-range AFM phase transitions are observed at T N1 ∼ 9 and T N2 ∼ 7 K. The frustration factor | |/T N1 ∼ 3 indicates that the system is moderately frustrated, which is identifiable by the

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... ken triangular symmetry within both ab and bc planes for the triclinic crystal structure. The magnetic isotherm at temperatures below T N2 shows a field-induced spin-flop transition, and a complete H -T phase diagram for the two-step AFM system is mapped. Ab initio band-structure calculations suggest that the strongest exchange coupling does not correspond to the shortest Co-Co distance along the a axis but rather along the diagonal direction through a Co-O-W-O-Co supersuperexchange path within the bc plane.