Mingxin Zhang

Magnetic states in vacancy-containing transition-metal chalcogenides are highly sensitive to subtle changes in composition and local atomic environment, providing a useful setting for exploring competing magnetic interactions. Cr3Se4, with its defect NiAs-type framework and composition-dependent magnetism, provides a useful platform for investigating the sensitivity of magnetic states to chemical modification. Here, we report the growth and physical properties of Nb-containing Cr3Se4-type single crystals. The monoclinic structure is preserved upon introducing a small amount of Nb, whereas magnetic measurements reveal, besides the antiferromagnetic transition near 170 K, a broadened sequence of anomalies between approximately 50 and 100 K with a prominent feature around 70 K, followed by magnetic irreversibility at lower temperatures. Specific heat measurements resolve corresponding thermodynamic features, and magnetotransport measurements show a sizable negative magnetoresistance together with a distinct change across the intermediate-temperature regime. These observations demonstrate that weak chemical modification can substantially reshape the low-temperature magnetic evolution of Cr3Se4-type materials, offering a route for tuning the competing magnetic states of vacancy-containing chromium chalcogenides.