Spintronic Quantum Phase Transition in a $Graphene/P{b}_{0.24}S{n}_{0.76}Te$ Heterostructure with Giant Rashba Spin-Orbit Coupling

Abstract

Mechanical stacking of two dissimilar materials often has surprising consequences for heterostructure behavior. In particular, a two-dimensional electron gas (2DEG) is formed in the heterostructure of the topological crystalline insulator Pb0.24Sn0.76Te and graphene due to contact of a polar with a nonpolar surface and the resulting changes in electronic structure needed to avoid polar catastrophe. We study the spintronic properties of this heterostructure with non-local spin valve devices. We observe spin-momentum locking at lower temperatures that transitions to regular spin channel transport only at ~40 K. Hanle spin precession measurements show a spin relaxation time as high as 2.18 ns. Density functional theory calculations confirm that the spin-momentum locking is due to a giant Rashba effect in the material and that the phase transition is a Lifshitz transition. The theoretically predicted Lifshitz transition is further evident in the phase transition-like behavior in the Landé g-factor and spin relaxation time.

33 pages, 17 figures, supplemental information included

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• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• Magnetic 2D materials and heterostructures
• Graphene Spintronics
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• Magnetotransport in graphene/Pb0.24Sn0.76Te heterostructures: finding a way to avoid catastrophe

Cited by in corpus (1)

• Large-Area Intercalated 2D-Pb/Graphene Heterostructure as a Platform for Generating Spin-Orbit Torque