Multifunctional properties of Cr-doped Sb2Te3: A comprehensive investigation into optoelectronic, magnetic, thermoelectric, and mechanical characteristics

Abstract

The quest for multifunctional materials is vital for next-generation technologies in energy conversion, optoelectronics, and spintronics. Antimony telluride (Sb₂Te₃) stands out for its remarkable thermoelectric, optical, and topological properties but faces limitations like moderate thermoelectric efficiency and high thermal conductivity. This study investigates the impact of chromium (Cr) doping on Sb₂Te₃’s optoelectronic, magnetic, thermoelectric, and mechanical properties using DFT + U calculations. Cr incorporation significantly alters the electronic structure, inducing bandgap narrowing and pronounced spin splitting. The resulting spin-dependent band shifts enhance electrical conductivity while preserving a substantial Seebeck coefficient. DOS analyses reveal localized Cr-d states near the Fermi level, increasing carrier concentration and spin polarization. Magnetic analyses show that Cr’s large magnetic moment (3.77053 μB) drives ferromagnetic ordering, with a total moment of 4.00016 μB, highlighting potential for spintronic devices and quantum computing via the quantum anomalous Hall effect (QAHE). Thermoelectric evaluations demonstrate improved ZT values due to enhanced electrical conductivity and reduced lattice thermal conductivity from phonon scattering. The Seebeck coefficient remains favorable across temperatures, with spin-dependent variations suggesting applications in spin-caloritronics. Mechanical assessments reveal that Cr doping enhances Sb₂Te₃’s structural stability and mechanical robustness. Elastic constants (C₁₁, C₃₃) increase upon doping, reflecting improved resistance to uniaxial deformation. Enhanced shear constants (C₄₄, C₆₆) indicate better shear resistance, while bulk modulus (40.2 GPa), shear modulus (25.6 GPa), and Young’s modulus (64.8 GPa) confirm increased stiffness. The Poisson’s ratio (0.28) suggests that the doped material retains sufficient ductility for practical applications, and the improved Vickers hardness (2.9 GPa) signifies better wear resistance. These mechanical improvements ensure the material’s suitability for devices subjected to mechanical stress. Optically, Cr doping increases absorption in the visible and infrared regions, making the material suitable for solar cells, infrared detectors, and photonic devices. Modified dielectric and energy loss functions reflect improved light-matter interactions and reduced reflectivity. Overall, Cr-doped Sb₂Te₃ exhibits a synergistic enhancement of its multifunctional properties, including electronic, magnetic, thermoelectric, mechanical, and optical characteristics. These comprehensive improvements position it as a strong candidate for spintronics, thermoelectric generators, and optoelectronic technologies, laying the groundwork for future experimental validation and device integration.