Nanoscale Imaging of Ultralong-Lived Topological Edge States in 1T′-MoTe 2 at Room Temperature

The quantum spin Hall effect in 1T′-phase MoTe 2 promises topological protection at >250 K, yet direct observation of its nonequilibrium dynamics has remained elusive, requiring nanoscale spatial and ultrafast temporal resolution. Here, we employ time-resolved photoemission electron microscopy to visualize the carrier dynamics in bilayer 1T′-MoTe 2 at room temperature. We identify a topological edge mode spatially confined below 200 nm, exhibiting photoemission intensity an order of magnitude stronger than the bulk. Strikingly, the edge state shows an ultralong lifetime exceeding 3.2 ps, in stark contrast to the sub-100 fs relaxation of bulk states, a dynamical dichotomy that is absent in the topologically trivial 2H phase. Supported by first-principles calculations, we ascribe this robustness to spin-selective suppression of backscattering and electron–hole recombination in the helical edge channel. Our findings provide direct evidence of low-dissipation edge transport in a 2D-compatible system, advancing its prospects for ultrafast topological electronics and spintronics.