Vol. 7, Issue 1, Part B (2025)

The tunability of topological phases in low-dimensional quantum materials under external fields has emerged as a transformative strategy for designing next-generation quantum and nanoelectronic devices. This study systematically investigates the influence of electric fields, magnetic fields, mechanical strain, and multi-field coupling on the topological properties of two-dimensional (2D) quantum systems. Using a combination of ab initio density functional theory (DFT), tight-binding models, and experimental probes such as angle-resolved photoemission spectroscopy (ARPES), scanning tunneling microscopy (STM), and SQUID magnetometry, we demonstrate the controllable transition between trivial and topological phases, modulation of band gaps, and induction of Weyl and Dirac nodes under symmetry-breaking perturbations. Special emphasis is placed on the synergistic effects arising from dual or hybrid external fields. We also highlight how strain and pressure serve as non-destructive tools for phase tuning. Our results not only underscore the fundamental physics behind field-induced topological transitions but also offer a design blueprint for quantum field-effect transistors, spintronic and valleytronic devices, and topologically protected logic units. This tunability opens exciting avenues in reconfigurable quantum technologies where material properties can be dynamically tailored in real time.