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تسجيل مستخدم جديدLandau Level Spectroscopy of Dirac Electrons in a Polar Semiconductor with Giant Rashba Spin Splitting
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Optical excitations of BiTeI with large Rashba spin splitting have been studied in an external magnetic field ($B$) applied parallel to the polar axis. A sequence of transitions between the Landau levels (LLs), whose energies are in proportion to $sqrt{B}$ were observed, being characteristic of massless Dirac electrons. The large separation energy between the LLs makes it possible to detect the strongest cyclotron resonance even at room temperature in moderate fields. Unlike in 2D Dirac systems, the magnetic field induced rearrangement of the conductivity spectrum is directly observed.
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Strong Rashba effects at surfaces and interfaces have attracted great attention for basic scientific exploration and practical applications. Here, the first-principles investigation shows that giant and tunable Rashba effects can be achieved in KTaO$
_3$ (KTO) ultrathin films by applying biaxial stress. When increasing the in-plane compressive strain nearly to -5%, the Rashba spin splitting energy reaches $E_{R}=140$ meV, approximately corresponding to the Rashba coupling constant $alpha_{R}=1.3$ eV {AA}. We investigate its strain-dependent crystal structures, energy bands, and related properties, and thereby elucidate the mechanism for the giant Rashba effects. Furthermore, we show that giant Rashba spin splitting can be kept in the presence of SrTiO$_3$ capping layer and/or Si substrate, and strong circular photogalvanic effect can be achieved to generate spin-polarized currents in the KTO thin films or related heterostructures, which are promising for future spintronic and optoelectronic applications.
The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids, and provides a cornerstone for the burgeoning field of semiconductor spintronics. It is typically assumed to manifest as a momentum-dependent splitting of
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The spin-splitting energy bands induced by the relativistic spin-orbit interaction in solids provide a new opportunity to manipulate the spin-polarized electrons on the sub-picosecond time scale. Here, we report one such example in a bulk Rashba-type
polar semiconductor BiTeBr. Strong terahertz electromagnetic waves are emitted after the resonant excitation of the interband transition between the Rashba-type spin-splitting energy bands with a femtosecond laser pulse circularly polarized. The phase of the emitted terahertz waves is reversed by switching the circular polarization. This suggests that the observed terahertz radiation originates from the subpicosecond spin-polarized photocurrents, which are generated by the asymmetric depopulation of the Dirac state. Our result provides a new way for the current-induced terahertz radiation and its phase control by the circular polarization of incident light without external electric fields.
We report a Rashba spin splitting of a two-dimensional electron gas in the topological insulator Bi$_2$Se$_3$ from angle-resolved photoemission spectroscopy. We further demonstrate its electrostatic control, and show that spin splittings can be achie
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We observe a giant spin-orbit splitting in bulk and surface states of the non-centrosymmetric semiconductor BiTeI. We show that the Fermi level can be placed in the valence or in the conduction band by controlling the surface termination. In both cas
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