Spontaneous and tunable valley polarization in two-dimensional single-layer LaCl 2

• Published in: Semiconductor science and technology 2024-07, Vol.39 (7), p.75006
• Main Authors: Liu, Hengbo, Li, Jia, Tian, Jianke, Li, Yan, Shi, Junjie
• Format: Article
• Language: English
• ISSN: 0268-1242; 1361-6641
• DOI: 10.1088/1361-6641/ad4e5f

Applying the valley contrasting properties of valleytronic materials to logical operations is the foundation of valleytronic device manufacturing. It is predicted that single-layer (SL) LaCl 2 is an ferrovalley material with intrinsic and tunable valley polarization through first-principles calculations. It is a ferromagnetic semiconductor (bandgap 0.767 eV) with roughly 1.0 μ B per unit cell as well as out of plane magnetization, and the Curie temperature is about 149 K. The tight-binding model considering five orbitals as well as next nearest neighboring hopping get a consistent band structure with the first-principles calculation. The valley polarization changes from 40.49 to 98.51 meV under the biaxial strain of 5% ∼ −5%. Therefore, the biaxial strain can be a means to tune the valley polarization. In addition, the valley polarization of the double-layer (DL) structure (∼80 meV) is much greater than that of the SL structure (∼59 meV) due to the increased magnetic moment of the DL structure, indicating the potential tunable character by stacking few layers. We believe that SL LaCl 2 has great potential for device manufacturing and application in the field of valley electronics.