First-principles investigation of half-metallic CaTGe₂O₆ (T = Mn, Fe, Co) clinopyroxenes: Potential for spintronics...

Clinopyroxene is a subgroup of pyroxene that is found in a variety of igneous and metamorphic rocks. This study investigates the structural, mechanical, electronic, optical, and thermal characteristics of CaTGe₂O₆ (T = Mn, Fe, Co) using density functional theory. These structures' lattice parameters have been optimized using GGA-PBE, GGA-PBESOL, and LDA exchange-correlation functionals, where all these structures are found to be stable in monoclinic symmetry having a little variation with experimental results. All the structures are mechanically stable and ductile in nature. The CaFeGe₂O₆ has the highest melting point and Debye temperature among the three structures. The electronic band diagram and spin-polarized PDOS of these structures confirm the half-metallic nature of all three structures. The half-metallic band gaps of CaTGe₂O₆ (T = Mn, Fe, Co) are 3.05, 1.69, 1.99 eV in GGA + U and 2.88, 1.52, 1.78 eV in the LDA + U method, respectively. CaMnGe₂O₆ is metallic in the spin-up state, whereas both CaFeGe₂O₆ and CaMnGe₂O₆ are metallic in the spin-down state. Refractive indices and dielectric functions of these structures ensure the transparency of CaTGe₂O₆ (T = Mn, Fe, Co) clinopyroxenes around 28.5 eV photon energy. These structures possess the highest reflectivity and absorption coefficients in the UV region. These salient features of these structures suggest that the spintronics and optoelectronics industries may benefit from these clinopyroxene structures in the future.