Magnetic properties of the S = 52 anisotropic triangular chain compound Bi3FeMo2 O12

Competing magnetic interactions in low-dimensional quantum magnets can lead to the exotic ground state with fractionalized excitations. Herein, we present our results on an S=52 quasi-one-dimensional spin system Bi3FeMo2O12. The structure of Bi3FeMo2O12 consists of very well separated, infinite zigzag S=52 spin chains. The observation of a broad maximum around 10 K in the magnetic susceptibility χ(T) suggests the presence of short-range spin correlations. χ(T) data do not fit the S=52 uniform spin chain model due to the presence of second-nearest-neighbor coupling (J2) along with the first-nearest-neighbor coupling (J1) of the zigzag chain. The electronic structure calculations infer that the value of J1 is comparable with J2 (J2/J1≈1.1) with a negligible interchain interaction (J′/J≈0.01) implying that Bi3FeMo2O12 is a highly frustrated triangular chain system. The absence of magnetic long-range ordering down to 0.2 K is seen in the heat-capacity data, despite a relatively large antiferromagnetic Curie-Weiss temperature θCW≈-40 K. The magnetic heat capacity follows nearly a linear behavior at low temperatures indicating that the S=52 anisotropic triangular chain exhibits the gapless excitations.