Chiral Photocurrent in a Quasi-1-D TiS3 (001) Phototransistor.

The presence of in-plane chiral effects, hence spin-orbit coupling, is evident in the changes in the photocurrent produced in a TiS3(001) field-effect phototransistor with left versus right circularly polarized light. The direction of the photocurrent is protected by the presence of strong spin-orbit coupling and the anisotropy of the band structure as indicated in NanoARPES measurements. Dark electronic transport measurements indicate that TiS3 is n-type and has an electron mobility in the range of 1-6 cm2V-1s-1. I-V measurements under laser illumination indicate the photocurrent exhibits a bias directionality dependence, reminiscent of bipolar spin diode behavior. Because the TiS3 contains no heavy elements, the presence of spin-orbit coupling must be attributed to the observed loss of inversion symmetry at the TiS3(001) surface.