Non-Lifshitz-Kosevich (LK) behavior in antiferromagnet SmPS.

The introduction of rare earth elements (Ln) in non-magnetic ZrSiS family activates the spin degree of freedom due to 4f-orbitals, which pave a way to realize novel quantum states. The LnSbTe (Ln = lanthanides) family of magnetic topological materials has drawn significant attention owing to the interplay between magnetism, topology, and electron correlations. Similar to LnSbTe, a distinct set of magnetic versions of LnPS can be realized, which exhibit a range of exotic properties. Here we report unusual quantum oscillation in SmPS. Despite its structural similarity to the ZrSiS family and the magnetic LnSbTe series, SmPS exhibits anomalous Shubnikov–de Haas (SdH) oscillations that cannot be described by the standard LK model over a wide temperature range. This deviation from canonical quantum oscillation behavior highlights canonical quantum oscillation behavior highlights the role of substantial interactions between the local magnetic moments and itinerant electrons. Our results position SmPS as a promising material for uncovering new physics beyond the conventional understanding of quantum oscillations in magnetic topological systems.