Crystal Structure, Charge Transport, and Magnetic Properties of MnSb 2 Se 4

A single phase of MnSb 2 Se 4 was synthesized by combining high‐purity elements at 773 K. Single‐crystal X‐ray diffraction revealed that MnSb 2 Se 4 is isostructural with FeSb 2 Se 4 crystallizing in the monoclinic space group C 2/ m with a = 13.076(3) Å, b = 3.965(2) Å, c = 15.236(4) Å, β = 115.1(2)°, Z = 4. MnSb 2 Se 4 melts congruently at 790 K and is thermally stable up to 1000 K. Electronic band structure calculations, infrared diffuse reflectance spectroscopy, and low‐temperature electronic transport data indicate that MnSb 2 Se 4 is a narrow‐bandgap p ‐type semiconductor with an energy bandgap of approximately 0.31 eV and exhibits a sharp increase in the resistivity near 230 K. A large Seebeck coefficient ( S = +945 μV K –1 ), high electrical resistivity ( ρ ≈ 9 Ω m), and low thermal conductivity ( κ = 1.4 W m –1  K –1 ) were observed at 300 K. Direct current (DC) magnetic‐susceptibility measurements indicated that MnSb 2 Se 4 is paramagnetic at 300 K and undergoes an order/disorder antiferromagnetic transition with a Néel temperature of approximately 20 K. Alternating current (AC) susceptibility at various frequencies suggested a spin‐glass‐like behavior.