First-principles Study On The Magnetism Of Silicene Doped With Metal Atoms Under External Field

Silicene is a new kind of two-dimensional nanomaterials,and it is proven that the stable monolayer silicene existed not only theoretically but also experimentally.Due to high value in the practical applications,there are extensive researches on silicene to study its properties.Among these properties,magnetism has attracted much interests.In our work,we adopt the first-principles calculations to study the structures,electronic and magnetic properties of the metal atoms doped silicenes.In addition,we study the changes of magnetism in metal atoms doped silicenes under the external field and external strain.We study the structures,electronic and magnetic properties of the silicenes doped with 3d transition metal atoms(Sc-Ni),Cu atom and Zn atom.Except Zn atom doped silicene,other metal atoms(Sc-Cu)doped silicenes have two stable structures and these doped systems have different symmetries.Besides,we find that some metal atom doped silicene have different magnetic properties compared with the metal atom doped graphene.We study the electronic and magnetic properties of metal atoms doped silicenes under external electric field.For the high concentration of Fe doped silicene,the doped system shows prominent switch effect.For the low concentration of Fe and Cr doped silicenes,different doped systems show different magnetoelectric(ME)behaviors.For one structure of Fe doped silicene,the magnetic moment is 0?Bwhen the electric field is postive,and the magnetic moment increases linearly with the decreasing negative electric field.This kind of the ME behaviors is called ME diode.For both the high concentrations and low concentrations of Fe or Cr doped silicene,there exist a linear region of magentic moment under external field.The magnetism of silicon-based nanomaterials can be affected by the external strain.We apply the external strain on the Cr and Fe doped silicenes,and find prominent changes of magnetic moment.When the isotropic tensile strain reaches a small value,we find that the magnetic states of Cr and Fe doped silicenes change from low spin states to high spin states(4?B).For the uniaxial tensile strain applied on the metal atom doped silicenes,the magnetic states of Fe doped silicene can change from a nearly nonmagnetic state to a higher magnetic state(2?B),and the magnetic moment of Cr doped silicene can gradually increase to 4?B.We find that the magnetic properties of Cr and Fe doped silicenes are sensitive to the magnitude and direction of the external strain.