Hydroxyl induced edge magnetism and metallicity in armchair MoS2 nanoribbons

Based on ab initio density functional theory, we demonstrate systematically how nonmagnetic semiconductor armchair MoS2 nanoribbons (AMoS(2)NRs) become magnetic or/and metallic when being edge-passivated by OH groups. Both the Mo and S edge atoms of an AMoS(2)NR can adsorb OH groups but an S atom can catch one OH group only when each of its neighbor Mo atoms has already been passivated by two. The AMoS(2)NR becomes edge magnetic in low passivation density and edge conductive in high density. In the case of uniform edge passivation, one or both of the edges usually become metallic and nonmagnetic if the number i of OH groups per primitive cell satisfies 1 <= i < 8. In case i < 1 a non-passivated edge Mo atom may be spin polarized if its neighbor Mo atom has adsorbed one OH group and the nanoribbon becomes magnetic semiconductor. For i = 8 the nanoribbon become nonmagnetic semiconductor again.