Light-induced pure spin transportation in twisted atomic wires of transition metal trichalcogenides

Twisting of van der Waals layered materials induces numerous exotic quantum phenomena under symmetry reduction and long-range moir\'e potential with strong correlation, leading to the pursuit of twistronic materials at different dimensionalities. Here we show that twisted one-dimensional (1D) atomic wires also exhibit intriguing electronic and optical features, tunable by twist angles. By analyzing transition metal trichalcogenide atomic wires, which have been synthesized in experiments, we find that a single chain of $\mathrm{WT}{\mathrm{e}}_{3}$ natively favors a helical structure with a short torsional wavelength of 1.58 nm and a twist angle of 24\ifmmode^\circ\else\textdegree\fi{} as its energy minimum. Twisting the atomic wire azimuthally could realize a metal-to-semiconductor transition and a symmetry-protected persistent spin helix texture. In addition, we propose a light-induced pure spin current generation without a net electric charge current, indicating magnetic moment accumulation at the ends of twisted wires and a sizable spin voltage along the axial direction. These results shed light on exploiting 1D materials for twistronics and chiral spintronics.