Magnetic and Transport Properties of Ba₆Fe₈S₁₅ and BaFe₂S₃: Magnetoresistance in a Spin-Glass-Like Fe(II) System

The magnetic and transport properties of the Hong and Steinfink 1-dimensional barium iron sulfide phases BaFe 2 S 3 and Ba 6 Fe 8 S 15 were studied. The valence precise BaFe 2 S 3 phase (Fe 2+ ) is semiconducting with a nonmagnetic ground state due to strong intrachain antiferromagnetic coupling. However, short-range magnetic correlations and spin-glass-like behavior are found below 25 K, which gives rise to a magnetoresistive effect of 10% at 9 T. BaFe 2 S 3 is a rare example of a magnetoresistive ternary sulfide. The mixed valent Ba 6 Fe 8 S 15 phase (Fe 2 .25 + ) is also a semiconductor with a nonmagnetic ground state. Ba 6 Fe 8 S 15 shows similar spin-glass-like behavior but at a lower temperature ( T f = 15 K). Comparisons with other tetrahedrally coordinated iron sulfide phases and possible origins of the short-range magnetic correlations are discussed.