Canted ferromagnetic order in a distorted triangular-lattice magnet Na₂SrCo(VO₄)₂

Triangular-lattice cobaltates with glaserite-type X₂YCo(TO₄)₂ structure provide an ideal platform to investigate intriguing quantum magnetism. Here we report a comprehensive study of the structural and magnetic properties of a triangular-lattice cobalt vanadate Na₂SrCo(VO₄)₂. Room-temperature x-ray and neutron powder diffraction confirm that Na₂SrCo(VO₄)₂ crystallizes in the monoclinic P2_1/c space group with slightly distorted triangular layers of Co²⁺ ions. Magnetization measurements reveal a ferromagnetic transition at TC ≈ 3.4K, where a sharp λ-type anomaly is observed in the specific heat. The magnetic entropy recovered up to 55 K approaches 90% of Rln2, supporting an effective spin-1/2 state of Co²⁺ ions at low temperature. Neutron diffraction at 2.3 K (below T_C) further confirms a long-range canted ferromagnetic order with the Co²⁺ moments aligned in the ac plane and the ordered moment size of ∼ 2.6 μB. Comparing with its sister compounds with a trigonal symmetry, Na₂BaCo(VO₄)₂ with a collinear ferromagnetic structure and the recently discovered spin supersolid candidate Na₂BaCo(PO₄)₂ with a distinct Y-like antiferromagnetic ground state, this study indicates the decisive role of the TO₄ tetrahedra in tuning exchange interactions and contrasting magnetic behaviors of these glaserite-structure compounds.