The angular-dependent magnetoresistance (AMR) of the ab plane is measured on single crystals iron-chalcogenide FeSe 1– x S ( = 0, 0.07, 0.13 and 1) y Te 0.06, 0.61 at various temperatures under fields up to 9 T. A pronounced twofold-anisotropic carrier-scattering effect identified by AMR, attributed a magnetic-field-induced spin nematicity that emerges from tetragonal normal-state regime below ...