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Updated: Aug 25, 2026
Measurement of Coherence Decay in GaMnAs Using Femtosecond Four-wave Mixing
Published on: December 3, 2013
Laporte Selection Rule Induced the Suppression of d-d Transitions and Vacancies Enhanced the Second Harmonic
Weiping Guo1,2, Ya Yang3, Yi Fang1,2
1Key Laboratory of Eco-materials Advanced Technology, Key Laboratory of Advanced Materials Technologies International (HongKong Macao and Taiwan) Joint Laboratory on Advanced Materials Technologies, College of Materials Science and Engineering, Fuzhou University, Fuzhou, People's Republic of China.
Abstract:
The d-d transitions lead to strong orbital hybridization near the band edge, decreasing the band gap (Eg) for magnetic transition metal chalcogenides. The small Eg seriously limits the high laser-induced damage threshold (LIDT) of the mid-infrared (IR) nonlinear optical (NLO) crystal. Herein, a quasi-centrosymmetric (quasi-CS) [MnS4] tetrahedron is proposed to suppress the d-d transitions by the Laporte selection rule in I -MnGa2S4 for the first time, leading to the largest Eg of 3.43 eV in magnetic transition metal NLO sulfides. The partial density of states calculations indicate that the Mn-3d orbital hardly contributes to the optical transitions in [MnS4] tetrahedron. Meanwhile, the consistent arrangement of tetrahedral motifs and cation vacancies in defect chalcopyrite I -MnGa2S4 improve the second harmonic generation (SHG) response. As a result, the I -MnGa2S4 possesses a large SHG response of 2.1 × AgGaS2 (AGS) and a high polycrystalline LIDT of 8.15 × AGS. In addition, the isomorphic solid-solution I -MnGa2SexS4- x (x = 1, 2, 2.8, and 4) exhibit an enhanced SHG response of 4.6 × AGS for I -MnGa2Se4.
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