title: Intrinsic magnetism of grain boundaries in two-dimensional metal dichalcogenides.
abstract: Grain boundaries (GBs) are structural imperfections that typically degrade the performance of materials. Here we show that dislocations and GBs in two-dimensional (2D) metal dichalcogenides MX2 (M = Mo, W; X = S, Se) can actually improve the material by giving it a qualitatively new physical property: magnetism. The dislocations studied all display a substantial magnetic moment of ∼1 Bohr magneton. In contrast, dislocations in other well-studied 2D materials are typically nonmagnetic. GBs composed of pentagon-heptagon pairs interact ferromagnetically and transition from semiconductor to half-metal or metal as a function of tilt angle and/or doping level. When the tilt angle exceeds 47°, the structural energetics favor square-octagon pairs and the GB becomes an antiferromagnetic semiconductor. These exceptional magnetic properties arise from interplay of dislocation-induced localized states, doping, and locally unbalanced stoichiometry. Purposeful engineering of topological GBs may be able to convert MX2 into a promising 2D magnetic semiconductor.
authors.affiliation: Department of Mechanical Engineering and Materials Science, Department of Chemistry, and the Smalley Institute for Nanoscale Science and Technology, Rice University , Houston, Texas 77005, United States.
authors.forename: Zhuhua
authors.initials: Z
authors.lastname: Zhang
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Zou
authors.forename: Vincent H
authors.initials: VH
authors.lastname: Crespi
authors.forename: Boris I
authors.initials: BI
authors.lastname: Yakobson