ARPES and transport studies of the elemental topological insulator $\alpha$-Sn

Abstract

Gray tin, also known as $\alpha$-Sn, can be turned into a three-dimensional topological insulator (3D-TI) by strain and finite size effects. Such room temperature 3D-TI is peculiarly interesting for spintronics due to the spin-momentum locking along the Dirac cone (linear dispersion) of the surface states. Angle resolved photoemission spectroscopy (ARPES) has been used to investigate the dispersion close to the Fermi level in thin (0\,0\,1)-oriented epitaxially strained films of $\alpha$-Sn, for different film thicknesses as well as for different capping layers (Al, AlO${}_x$ and MgO). Indeed a proper capping layer is necessary to be able to use $\alpha$-Sn surface states for spintronics applications. In contrast with free surfaces or surfaces coated with Ag, coating the $\alpha$-Sn surface with Al or AlO${}_x$ leads to a drop of the Fermi level below the Dirac point, an important consequence for transport is the presence of bulk states at the Fermi level. $\alpha$-Sn films coated by AlO${}_x$ are studied by electrical magnetotransport: despite clear evidence of surface states revealed by Shubnikov-de Haas oscillations, an important part of the magneto-transport properties is governed by "bulk" electronic states attributed to the $\Gamma 8$ band, as suggested by {\it ab-initio} calculations.

References in corpus (22)

• Topological insulators and superconductors
• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• Quantum Spin Hall Effect in Graphene
• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Spin Hall effect
• Direct electronic measurement of the spin Hall effect
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• Topological origin of subgap conductance in insulating bilayer graphene
• Room temperature spin-orbit torque switching induced by a topological insulator
• Fermi level dependent charge-to-spin current conversion by Dirac surface state of topological insulators
• Spin-pumping into surface states of topological insulator α-Sn, spin to charge conversion at room temperature
• Room temperature magnetization switching in topological insulator-ferromagnet heterostructures by spin-orbit torques
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• Universal Fabrication of Two-Dimensional Electron Systems in Functional Oxides
• Elemental Topological Insulator with a Tunable Fermi Level: Strained α-Sn on InSb(001)
• Elemental topological Dirac semimetal: α-Sn on InSb(111)
• Tuning a Schottky barrier in a photoexcited topological insulator with transient Dirac cone electron-hole asymmetry
• Dirac cone with helical spin polarization in ultrathin $\alpha$-Sn(001) films
• Quantum oscillations and Berry's phase in topological insulator surface states with broken particle-hole symmetry
• The topological surface state of $\alpha$-Sn on InSb(001) as studied by photoemission

Cited by in corpus (12)

• Ultrafast spin-charge conversion at SnBi${}_2$Te${}_4$/Co topological insulator interfaces probed by terahertz emission spectroscopy
• Growth and Magnetotransport in Thin Film α-Sn on CdTe
• Tailoring the topological surface state in ultrathin $\alpha$-Sn (111) films
• Thermal Stability Enhancement in Epitaxial α-Sn Films by Strain Engineering
• Structural and electronic properties of the pure and stable elemental 3D topological Dirac semimetal $\alpha$-Sn
• Spin-orbit torques and magnetotransport properties of $\alpha$-Sn and $\beta$-Sn heterostructures
• Dielectric and electronic properties of three-dimensional Luttinger semimetals with a quadratic band touching
• Anatomy of plasmons in generic Luttinger semimetals
• 3D Topological Semimetal Phases of Strained $\alpha$-Sn on Insulating Substrate
• Non-orthogonal Spin-Momentum Locking
• Predication of topological states in the allotropes of group-IV elements
• Elemental topological Dirac semimetal α-Sn with high quantum mobility