Large-Scale 2D Materials Integration for Spintronics

The discovery of graphene has opened novel exciting opportunities in terms of functionalities and performances for spintronics devices. This started a wide exploration of a large variety of 2D crystals for spintronics with the hope to exploit some of their unique topological properties. We will present here experimental results concerning integration of 2D materials in vertical Magnetic Tunnel Junctions (MTJ). We will first focus on the archetypical graphene material. We will show that a thin graphene passivation layer, directly integrated by low temperature catalyzed chemical vapor deposition (CVD) [1], allows to preserve a highly surface sensitive spin current polarizer/analyzer behavior in functional devices. The direct growth of the 2D layer prevents the oxidation of the ferromagnet also enabling the use of novel processes for spintronics devices. We will illustrate this property by demonstrating the use of Atomic Layer Deposition (ALD) processes to fabricate efficient spin valves.[2] Characterizations of complete functional spin valves making use of 2D layers grown by CVD will then be presented. We will further discuss the integration in spin-valves by CVD of other 2D materials beyond graphene, including the 2D insulator h-BN, 2D semiconductors and beyond.[3] Finally, we will expand the discussion to a novel pulsed laser deposition (PLD) approach for the definition of complex van der Waals heterostructures of 2D materials in magnetic tunnel junctions.[4] This PLD growth approach unlocks the association in heterostructure of wide families of multifunctional 2D materials, including the most delicate ones. The different presented experiments unveil promising approaches for the quantum engineering of multifunctional 2D materials heterostructures for spintronics.<br/>[1] Dlubak et al. ACS Nano 6, 10930 (2012); Weatherup et al. 6, 9996 ACS Nano (2012); Naganuma et al. APL 116, 173101 (2020)<br/>[2] Dlubak et al. APL 100, 173113 (2012) ; Martin et al. ACS Nano 8, 7890 (2014) ; Kern et al. APL 114, 053107 (2019) ; Piquemal-Banci et al. Nature Communications 11, 5670 (2020)<br/>[3] Piquemal-Banci et al. ACS Nano 12, 4712 (2018) ; Zatko et al. ACS Nano 13, 14468 (2019) ; Och et al. Nanoscale 13, 2157 (2021)<br/>[4] Godel et al. ACS Applied Nano Materials 3, 7908 (2020) ; Zatko et al. ACS Nano 15, 7279 (2021)