研究目的
To investigate the use of an electric field to achieve a large valley splitting in the van der Waals (vdW) heterostructure WSe2/CrI3, as an alternative to commonly used means such as the magnetic field.
研究成果
The study demonstrates that an electric field can realize a large valley splitting in the vdW heterostructure WSe2/CrI3, comparable to the effect of a magnetic field over 50 T. The underlying physics originates from the distinct exchange interactions with the opposite helicities of pseudospin between the K and K′ points, and the interlayer charge transfer where spin conservation plays a role. This finding provides a new method for controlling valley splitting, promising for potential applications in information processing.
研究不足
The study is based on theoretical calculations and may not fully account for all experimental conditions. The valley splitting achieved is dependent on the specific electric field applied and the alignment of pseudospin and spin, which may vary in practical applications.
1：Experimental Design and Method Selection:
The study is based on first-principles calculations using the Kohn–Sham theory and the projector augmented wave (PAW) pseudopotentials as implemented in VASP. The exchange-correlation potential is in the form of Perdew–Burke–Ernerhof (PBE) with the generalized gradient approximation (GGA). The zero damping DFT-D3 method of Grimme was taken to include the vdW interactions.
2：Sample Selection and Data Sources:
The vdW heterostructure WSe2/CrI3 is constructed by taking a 2 × 2 supercell of WSe2 to match the unit cell of CrI3 based on their optimized lattice constants.
3：List of Experimental Equipment and Materials:
The calculations were performed using VASP software.
4：Experimental Procedures and Operational Workflow:
Structural optimization was performed with the energy convergence threshold set to 10?5 eV and the residual force on each atom less than
5：05 eV ??The cutoff energy for the plane-wave basis is set to 500 eV. The Brillouin zone is sampled with Γ centered Monhorst–Pack grids of 4 × 4 × A vacuum distance larger than 15 ? along the z direction was used in the supercell geometry to eliminate interaction between the heterostructure and its periodic images. Data Analysis Methods:
The band structure and valley splitting were analyzed based on the calculated eigenvalues and charge distributions.
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