Magnetic ground state of Rb2Ni3S4

Determine whether the magnetic ground state of Rb2Ni3S4 is weakly ferromagnetic or paramagnetic.

Background

The magnetic ground state of Rb2Ni3S4 has conflicting experimental interpretations. Early reports suggested weak ferromagnetism, whereas later measurements favored a paramagnetic ground state. The authors’ susceptibility data show no clear anomaly near the insulating transition, and the reported effective moment per Ni atom is extremely small, so the magnetic state remains unresolved.

This question is distinct from the paper’s proposed vibronic interpretation of the insulating transition: the authors explicitly state that the material’s magnetic ground state remains debated rather than establishing it.

References

Magnetism is also unlikely to be the dominant driving force: although the magnetic ground state of $\mathrm{Rb_2Ni_3S_4}$ remains debated, with early reports suggesting weak ferromagnetism [27] and later studies favoring a paramagnetic ground state [28], our susceptibility measurements show no clear anomaly near $T{*}$ [Fig. 1(d)], and the reported effective moment per Ni atom is extremely small [24].

— Emergent Vibronic Spectral Hierarchy in a Kagome Flat-Band Insulator  (2608.21250 - Shu et al., 21 Aug 2026) in Results and Discussion, Section 1, “Weak first-order phase transition”