Li2MnSnSe4: A New Quaternary Diamond‐Like Semiconductor with Nonlinear Optical Response and Antiferromagnetic Property

A new selenide with a diamond‐like structure, Li₂MnSnSe₄, was synthesized for the first time by using a conventional high‐temperature solid‐state reaction method. Li₂MnSnSe₄ crystallizes in the space group Pmn 2₁ (no. 31) of the orthorhombic system. Its three‐dimensional framework is constructed by corner‐sharing LiSe₄, MnSe₄, and SnSe₄ tetrahedra. The title compound has been discovered to have both type I phase‐matchable behavior and to exhibit moderate powder second‐harmonic generation intensity, about 0.5 times that of commercial AgGaS₂ in the particle size of 200–250 μm at a laser radiation of 2.09 μm. In addition, Li₂MnSnSe₄ exhibits congruent melting behavior, which makes the bulk single‐crystal growth by the Bridgman–Stockbarger method possible. The temperature‐dependent susceptibility measurement indicates an antiferromagnetic interaction with a Néel temperature (T _N) of 8.6 K for this compound.