Electronic control of combined spin-orbit and magnetic exchange coupling in graphene van der Waals-heterostructures (CombSOC)

该项目旨在结合范德华异质结构中的自旋-轨道耦合(SOC)和磁邻近效应，在石墨烯的能带结构中印记定制的、电可调的自旋极化。在非掺杂(2D磁体/石墨烯/2D SOC材料)异质三层膜中，CombSOC设想通过实验演示石墨烯电荷中性点附近的面内磁各向异性和拓扑间隙开口，并探索它们的强度是否可以通过外部刺激(如外加电场)来控制。通过比较，在电荷转移掺杂的异质三层膜中，CombSOC试图揭示高掺杂石墨烯层中远离电荷中性点的诱导自旋极化及其对集体自旋和电荷激发的影响。我们将用互补电子和光电光谱来研究二次近邻的石墨烯。虽然磁输运实验将揭示电荷中性点附近的磁各向异性和拓扑间隙开口，但自旋阀测量将得出自旋寿命各向异性。此外，自旋相关的隧道谱被用来量化远离电荷中性点的自旋极化。利用在近红外和中红外区域的时间分辨共振光电流光谱，将从根本上表征各向异性光电流的对称性和动力学，这些电流与近化石墨烯中与自旋相关的带间跃迁有关。

This project aims to combine spin-orbit coupling (SOC) and magnetic proximity effects in van der Waals heterostructures to imprint tailored and electrically tunable spin polarizations in the band structure of graphene. In undoped (2D magnet/graphene/2D SOC material) heterotrilayers, CombSOC envisions to experimentally demonstrate the in-plane magnetic anisotropies and topological gap openings close to the charge neutrality point of graphene arising from the combined proximity, and explore whether their strength can be controlled through external stimuli, such as an externally applied electric displacement field. By comparison, in charge transfer doped heterotrilayers, CombSOC seeks to reveal the induced spin polarizations far away from the charge neutrality point and their impact on emergent collective spin and charge excitations in the highly doped graphene layer. The double-proximitized graphene will be investigated by complementary electronic and optoelectronic spectroscopies. While magnetotransport experiments shall reveal the magnetic anisotropies and topological gap openings near the charge neutrality point, spin valve measurements will yield the spin lifetime anisotropy. Moreover, spin-dependent tunneling spectroscopy is utilized to quantify the spin polarizations away from the charge neutrality point. Using a time-resolved, resonant photocurrent spectroscopy in the near and mid-infrared regime, the symmetries and dynamics of the anisotropic photogalvanic currents, which are linked to the spin-dependent interband transitions in the proximitized graphene, will be fundamentally characterized.