title: Tensile strain induced switching of magnetic states in NbSe2 and NbS2 single layers.
abstract: Two dimensional crystals, befitting nanoscale electronics and spintronics, can benefit strain-tunable applications due to their ultrathin and flexible nature. We show by first-principles calculations that tensile strain can enhance the exchange splitting of spins in NbSe2 and NbS2 single layers. Particularly, a switch from antiferro- to ferro-magnetism is realized by strain engineering. Under strains lower than 4%, an antiferromagnetic state with opposite spins aligned on the next-nearest-neighbor rows of Nb atoms is favored in energy due to a superexchange interaction; with higher strains the ground state turns to be ferromagnetic with a double exchange origin. In contrast, the VSe2 and VS2 single layers, though with the same trigonal prismatic coordination, remain ferromagnetic even under compressive strains.
authors.affiliation: State Key Laboratory of Mechanics and Control of Mechanical Structures, Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China. wlguo@nuaa.edu.cn.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xu
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Liu
authors.forename: Wanlin
authors.initials: W
authors.lastname: Guo