Inorganic antiferromagnetic semiconductors A2MnWO6 (A = Ba2+, Pb2+) as promising materials for optospintronics applications

Based on density functional theory (DFT), the structural, electronic, magnetic and optical properties of Mn2+ (3d5)-W6+ (5d0) based double perovskite oxides A2MnWO6 (A = Ba2+, Pb2+) were studied using the generalized gradient approximation (GGA) and by adding the exchange correlation effect (GGA + U). The crystal structures of two compounds were found to have cubic symmetry, space group Fm-3m, no 225, at room temperature. Both GGA and GGA + U calculations predicted a semiconducting-antiferromagnetic (AF-type1) behavior in A2MnWO6 compounds with energy gaps (Eg) in spin-up and spin-down except for (A = Pb2+), it exhibits ferrimagnetic (FI) metallic behavior within GGA. The value of Eg decreases with structure changing; Eg in (A = Pb2+; Eg = 0.54-2.11 eV) is smaller than in (A = Ba2+; Eg = 0.85-2.80 eV). Optical calculations show that the AF A2MnWO6 compounds have a good ability to absorb the incident photons due to their narrow Eg. The real and imaginary parts of the dielectric function show that these compounds also possess a great ability to retain the photon energy that it absorbed. It is believed that these materials could be synthesized experimentally, and they would prove useful for optospintronics applications.