Abstract
The ability to perform efficient electrical spin injection from ferromagnetic metals into two-dimensional semiconductor crystals based on transition metal dichalcogenide monolayers is a prerequisite for spintronic and valleytronic devices using these materials. Here, the hexagonal close-packed (hcp) interface electronic structure is investigated by first-principles calculations based on the density functional theory. In the lowest energy configuration of the hybrid system after optimization of the atomic coordinates, we show that interface sulfur atoms are covalently bound to one, two, or three cobalt atoms. A decrease of the Co atom spin magnetic moment is observed at the interface, together with a small magnetization of S atoms. Mo atoms also hold small magnetic moments, which can take positive as well as negative values. The charge transfers due to covalent bonding between S and Co atoms at the interface have been calculated for majority and minority spin electrons, and the connections between these interface charge transfers and the induced magnetic properties of the layer are discussed. Band structure and density of states of the hybrid system are calculated for minority and majority spin electrons, taking into account spin-orbit coupling. We demonstrate that bound to the Co contact becomes metallic due to hybridization between Co and S orbitals. For this metallic phase of , a spin polarization at the Fermi level of 16% in absolute value is calculated, which could allow spin injection into the semiconducting monolayer channel. Finally, the symmetry of the majority and minority spin electron wave functions at the Fermi level in the Co-bound metallic phase of and the orientation of the border between the metallic and semiconducting phases of are investigated, and their impact on spin injection into the channel is discussed.
1 More- Received 28 July 2016
- Revised 16 December 2016
DOI:https://doi.org/10.1103/PhysRevB.95.075402
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