Spin and valley transports in junctions of Dirac fermions

Abstract

We study spin and valley transports in junctions composed of silicene and topological crystalline insulators. We consider normal/magnetic/normal Dirac metal junctions where a gate electrode is attached to the magnetic region. In normal/antiferromagnetic/normal silicene junction, we show that the current through this junction is valley and spin polarized due to the coupling between valley and spin degrees of freedom, and the valley and spin polarizations can be tuned by local application of a gate voltage. In particular, we find a fully valley and spin polarized current by applying the electric field. In normal/ferromagnetic/normal topological crystalline insulator junction with a strain induced in the ferromagnetic segment, we investigate valley resolved conductances and clarify how the valley polarization stemming from the strain and exchange field appears in this junction. It is found that changing the direction of the magnetization and the potential in the ferromagnetic region, one can control the dominant valley contribution out of four valley degrees of freedom. We also review spin transport in normal/ferromagnetic/normal graphene junctions, and spin and valley transports in normal/ferromagnetic/normal silicene junctions for comparison.

13 pages, 10 figures

References in corpus (31)

• Electric Field Effect in Atomically Thin Carbon Films
• The electronic properties of graphene
• Half-Metallic Graphene Nanoribbons
• Chiral tunneling and the Klein paradox in graphene
• Topological Crystalline Insulators
• Unconventional quantum Hall effect and Berry's phase of 2pi in bilayer graphene
• Valley filter and valley valve in graphene
• Graphene field-effect-transistors with high on/off current ratio and large transport band gap at room temperature
• Emergence of magnetism in graphene materials and nanostructures
• Quantum interference and Klein tunneling in graphene heterojunctions
• Valley-Polarized Metals and Quantum Anomalous Hall Effect in Silicene
• Spin-orbit coupling in curved graphene, fullerenes, nanotubes, and nanotube caps
• Selective transmission of Dirac electrons and ballistic magnetoresistance of \textit{n-p} junctions in graphene
• Evidence of Klein tunneling in graphene p-n junctions
• The space group classification of topological band insulators
• Transport measurements across a tunable potential barrier in graphene
• Spin transport in proximity induced ferromagnetic graphene
• Electronic transport and quantum Hall effect in bipolar graphene p-n-p junction
• Intervalley scattering, long-range disorder, and effective time reversal symmetry breaking in graphene
• Spin-Valleytronics in Silicene: Quantum-Spin-Quantum-Anomalous Hall Insulators and Single-Valley Semimetals
• Chiral anomaly, Charge Density Waves, and Axion Strings from Weyl Semimetals
• Tunneling conductance of graphene NIS junctions
• Spin Injection into a Graphene Thin Film at Room Temperature
• Pseudospin valve in bilayer graphene: towards graphene-based pseudospintronics
• Controllable spin transport in ferromagnetic graphene junctions
• Contact resistance and shot noise in graphene transistors
• Dirac-fermions and conductance-oscillations in (s,d)-wave superconductor/normal graphene junctions
• Spontaneous Symmetry Breaking and Quantum Hall Effect in Graphene
• A supercurrent switch in graphene $\pi$-junctions
• Spin-polarized (001) surface states of the topological crystalline insulator Pb_{0.73}Sn_{0.27}Se
• Exact solutions for a type of electron pairing model with spin-orbit interactions and Zeeman coupling