Speaker
Description
Heterostructures of transition metal dichalcogenides and graphene provide vast utilization in proposals of novel platform devices [1] benefiting from the proximity-induced effects [2]. Monolayer $1$T-TaS$_2$ is a peculiar example as it is known for its low-temperature magnetism and charge density phase (CDW). The CDW arises as a spontaneous distortion in $1$T-TaS$_2$, forming the David star patterns [3]. The correlated state alters the electronic states of the proximitized graphene [4]. Focusing on the p$_z$ states of graphene, these effects can be captured within a tight-binding model, providing an insight into underlying proximity mechanisms.
Using the Kubo formalism, we study charge to spin interconversion effects in a $1$T-TaS$_2$/graphene heterostructure within the linear response regime. We investigate the impact of the magnetization direction in $1$T-TaS$_2$ on charge to spin interconversion efficiencies. Additionally, we explore different configurations of individual layers and identify the role of the tight-binding parameters in determining the ratio between the Rashba-Edelstein (REE) and the unconventional Rashba-Edelstein effect (UREE).
The (U)REE exhibits a non-trivial dependence on a chemical potential and is proportional to spin accumulation in the (parallel) perpendicular direction relative to the externally applied electric current. It is shown that the Rashba interaction plays a crucial role in the determination of charge to spin conversion coefficients, while the magnetization induces a relative shift of the Dirac cones manifesting in the additional non-analytical behaviour. Furthermore, the different stacking of $1$T-TaS$_2$ and graphene affects the Rashba phase, allowing a switch between UREE and REE.
Acknowledgements
This work has been funded by the EU NextGenerationEU through the Recovery and Resilience Plan for Slovakia under the project No. 09I03-03-V05-00008.
References
[1] J. Azadmanjiri et al., “Graphene-Supported 2D transition metal dichalcogenide van der waals heterostructures,” Applied Materials Today, vol. 19. Elsevier BV, p. 100600, Jun. 2020. https://doi.org/10.1016/j.apmt.2020.100600
[2] M. Gmitra and J. Fabian, “Proximity Effects in Bilayer Graphene on Monolayer WSe$_2$: Field-Effect Spin Valley Locking, Spin-Orbit Valve, and Spin Transistor,” Physical Review Letters, vol. 119, no. 14. American Physical Society (APS), Oct. 04, 2017. https://doi.org/10.1103/physrevlett.119.146401
[3] D. C. Miller et al., “Charge density wave states in tantalum dichalcogenides,” Physical Review B, vol. 97, no. 4. American Physical Society (APS), Jan. 17, 2018. https://doi.org/10.1103/physrevb.97.045133
[4] K. Szałowski et al., “Spin–orbit and exchange proximity couplings in graphene/1T-TaS2 heterostructure triggered by a charge density wave,” 2D Materials, vol. 10, no. 2. IOP Publishing, p. 025013, Feb. 23, 2023. https://doi.org/10.1088/2053-1583/acbb19
