High pressure phase of Ba2FeS3: An antiferromagnet with one-dimensional spin chains

In this work, we report on the discovery of the high-pressure phase of Ba2FeS3 with quasi one-dimensional (1D) spin chains, which was synthesized under high-pressure and high-temperature conditions. A systematic study was carried out via structural, transport, magnetic and thermodynamic measurements. The high-pressure phase of Ba2FeS3 (denoted by Ba2FeS3 (HP)) crystallizes in a K2AgI3-typed orthorhombic structure with the space group of Pnma (62) and the lattice parameters of a = 8.6831 (1) Å, b = 4.2973 (1) Å, and c = 17.0254 (2) Å, respectively, which consists of chains of corner-sharing FeS4 tetrahedra along the b axis. Ba2FeS3 (HP) undergoes a long-range antiferromagnetic transition at TN ∼56 K, above which the magnetic susceptibility curve exhibits a round hump behavior with the maximum temperature Tmax ∼110 K. In addition, the intrachain coupling Jintra is about −18 K obtained by using the Wagner-Friedberg model. The specific heat data suggest that the total magnetic entropy change ΔS caused by the long-range ordering transition is only ∼20% of the expected value for a S = 2 system. For comparison, the properties of K2CuCl3-typed Ba2FeS3 with similar quasi 1D spin chains were presented as well. Our results indicate that both compounds exhibit a typical feature expected for compounds with 1D spin chains. •The new phase of Ba2FeS3 was synthesized under high pressure conditions.•The structure and physical properties of two polymorphs of Ba2FeS3 were studied in detail.•High-pressure phase of Ba2FeS3 displays an antiferromagnetic ground state with one-dimensional spin chains.