Magnetic properties of S = 5/2 anisotropic triangular chain Bi3FeMo2O12

TL;DR

This study investigates the magnetic properties of Bi3FeMo2O12, revealing a highly frustrated S=5/2 anisotropic triangular chain with no long-range order and gapless excitations, highlighting complex magnetic interactions in low-dimensional quantum magnets.

Contribution

It provides the first detailed analysis of the magnetic interactions and frustration in Bi3FeMo2O12, combining experimental and electronic structure calculations to reveal a highly frustrated triangular chain system.

Findings

Presence of short-range spin correlations around 10 K

Comparable J1 and J2 exchange interactions (~1.1)

Absence of magnetic long-range order down to 0.2 K

Abstract

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 = 5/2 quasi-one-dimensional spin system Bi3FeMo2O12. The structure of Bi3FeMo2O12 consists of very well separated, infinite zig-zag S = 5/2 spin chains. The observation of a broad maximum around 10 K in the magnetic susceptibility suggests the presence of short-range spin correlations. Magnetic susceptibility data do not fit to S=5/2 uniform spin chain model due to the presence of 2nd nearest-neighbor coupling (J2) along with the 1st nearest-neighbor coupling J1 of the zig-zag chain. The electronic structure calculations infer that the value of J1 is comparable with J2 (J2/J1~1.1) with a negligible inter-chain 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 of -40 K. The magnetic heat capacity follows nearly a linear behavior at low temperatures indicating that the S = 5/2 anisotropic triangular chain exhibits the gapless excitations.