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

Abstract 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) A, b = 4.2973(1) A, and c = 17.0254(2) A, 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 percent 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.