First-principles examination of structural, electronic, magnetic, and optical properties of a free lead scintillating double perovskites \(A_2NaTaX_6\) (\(A = Cs\), Rb; \(X = Cl, Br, I)\)

This study employs a first-principles approach to comprehensively examine the structural, electronic, optical, and magnetic properties of the thermodynamically stable scintillating double perovskite halides \(A_2NaTaX_6\) $A_{2}NaTa{X}_6$ ( \(A = Cs, Rb\) $A=Cs,Rb$ ; \(X = Cl, Br, I\) $X=Cl,Br,I$ ). The dynamic stability of these materials were explained based on deduced phonon properties. Our analysis reveals that these compounds exhibit intriguing electronic behavior with spin polarization, demonstrating half-metallicity. In spin-up, the band gap is found to be zero, while in spin-down, it falls within the range of 3 to 4 eV with the incorporation of DFT+U corrections. Notably, the optical properties assessment highlights the exceptional UV and high-energy absorption capabilities of \(A_2NaTaI_6\) $A_{2}NaTa{I}_6$ , making it a promising candidate for scintillation applications in particle detection. This research sheds light on the unique and versatile properties of these materials, with implications for various technological and scientific applications.