Van der Waals heterostructures for spintronics and opto-spintronics (2110.09944v1)

Abstract: The large variety of 2D materials and their co-integration in van der Waals (vdW) heterostructures enable innovative device engineering. In addition, their atomically-thin nature promotes the design of artificial materials by proximity effects that originate from short-range interactions. Such a designer approach is particularly compelling for spintronics, which typically harnesses functionalities from thin layers of magnetic and non-magnetic materials and the interfaces between them. Here, we overview recent progress on 2D spintronics and opto-spintronics using vdW heterostructures. After an introduction to the forefront of spin transport research, we highlight the unique spin-related phenomena arising from spin-orbit and magnetic proximity effects. We further describe the ability to create multi-functional hybrid heterostructures based on vdW materials, combining spin, valley and excitonic degrees of freedom. We end with an outlook on perspectives and challenges for the design and production of ultra-compact all-2D spin devices and their potential applications in conventional and quantum technologies.

• The paper presents a systematic review showcasing how 2D van der Waals heterostructures enhance spin transport and enable voltage-controlled magnetism.
• It details proximity effects, including spin-orbit and magnetic interactions, that drive functionalities such as charge-to-spin conversion.
• Results highlight the integration of materials like graphene and TMDCs as key enablers for ultra-compact, low-power spintronic devices.

An Academic Review of 2D Van der Waals Heterostructures for Spintronic and Opto-Spintronic Applications

The research paper systematically explores the potential of van der Waals (vdW) heterostructures in the field of spintronics and opto-spintronics, with a particular focus on the utilization of two-dimensional (2D) layered materials. The integration of these 2D materials into layered vdW heterostructures is emphasized as a transformative approach, promising novel functionalities for developing ultra-compact and low-power electronic devices.

The paper provides a comprehensive overview of the advancements in 2D spintronic and opto-spintronic applications facilitated by vdW heterostructures. The authors delve into several unique spin-related phenomena, with a focus on proximity effects, including spin-orbit and magnetic interactions, which constitute the foundational mechanisms for new device functionalities. Notably, the paper discusses the creation of multi-functional hybrid heterostructures, taking advantage of diverse degrees of freedom, such as spin, valley, and excitonic dynamics.

The atomically-thin nature of 2D materials presents an opportunity for implementing strong electrostatic gating in contrast to conventional bulk materials. Such gating effects allow for significant manipulation of spintronic properties, as demonstrated by the authors’ discussions on gate-tunable carrier concentrations and voltage-controlled magnetism. Indeed, the authors highlight the expanded functionalities when integrating graphene, transition metal dichalcogenides (TMDCs), topological insulators (TIs), and 2D magnetic materials into vdW heterostructures. This integration not only leverages their individual material properties but also introduces novel traits via proximity interactions across interfaces.

Among significant topics discussed are proximity-induced spin phenomena. The paper details how vdW heterostructures can modify spin-orbit coupling (SOC) and magnetic properties, enhancing spin transport dynamics. For instance, the proximity-induced SOC, as observed in graphene-TMDC heterostructures, facilitates spin filtering, spin manipulation, and charge-to-spin interconversion (CSI) functionalities. The research underscores the possibilities and current challenges of employing such heterostructures in practical applications, including potential uses in spin interconnects, memory devices, and reconfigurable logics.

Solid empirical results and theoretical insights enrich the paper, particularly through the examination of spin injection and detection in 2D materials. For example, the utilization of 2D materials as tunnel barriers significantly enhances spin injection efficiencies, leading to novel demonstrations like optical spin injection in graphene using TMDCs. The paper further highlights the pronounced spin-relaxation anisotropy observed in graphene-TMDC interfaces due to proximity SOC, emphasizing its utility in tailoring spin transport properties.

In terms of applications, the implications are manifold. The potential for ultra-compact spin devices and their integration into existing and emerging quantum technologies is noted. The authors also emphasize opportunities for novel device architectures, including multilayer heterostructures with engineered SOC and magnetic exchange interactions, potentially leading to advances in spintronic devices with tailored functionalities such as spin-aspect logic or magnetic memory operations.

Looking forward, the paper suggests that advancements in material synthesis, layer intercalation, and stacking control could further amplify the capabilities of vdW heterostructures in spintronic applications. This underscores the avenue for tailoring spin interactions at atomic scales, a development that promises new frontiers in information processing technologies.

In conclusion, the review elaborates on the profound influence of proximity effects and external stimuli on the development of 2D material-based devices. The paper’s insights and analyses convey significant educational value, aligning current research efforts with future applications in spin-based technology domains. Such exploration is crucial for the continuous development of efficient, low-power, multi-functional electronic devices that harness the unique properties of vdW heterostructures.