Magnetodielectric Properties of Cu₂XSiS₄ (X=Mn, Fe) Single Crystals

Multiferroic materials are of great interest due to the coexistence of two or more ferroic order parameters within a single phase, leading to magnetoelectric phenomena through cross-coupling between magnetization and electric polarization. In this work, we investigated two promising multiferroic candidates, Cu₂MnSiS₄ and Cu₂FeSiS₄. High-quality single crystals of Cu₂XSiS₄ (X=Mn, Fe) were successfully grown using the chemical vapor transport (CVT) method, and their structural, magnetic, and dielectric properties were systematically characterized. Both compounds crystallize in the polar orthorhombic space group Pmn2₁ and exhibit antiferromagnetic ordering, with Néel temperatures (Tₙ) of approximately 8 K for Cu₂MnSiS₄ and 15 K for Cu₂FeSiS₄. Notably, Cu₂MnSiS₄ shows distinct magnetodielectric behavior below Tₙ, suggesting a possible magnetoelectric coupling. In contrast, Cu₂FeSiS₄ exhibits a metamagnetic transition near 3 K, indicative of a field-induced modification of its antiferromagnetic state, but no anomaly in its dielectric constant near Tₙ. These findings identify Cu₂MnSiS₄ as a new member of the polar chalcogenide family exhibiting potential multiferroic behavior.