Two-Fold-Symmetric Magnetoresistance in Single Crystals of Tetragonal BiCh2-Based Superconductor LaO0.5F0.5BiSSe March 2019 Two-Fold-Symmetric Magnetoresistance in Single Crystals of Tetragonal BiCh2-Based Superconductor LaO0.5F0.5BiSSe Journal of the Physical Society of Japan : [DOI:10.7566/JPSJ.88.033704]