Synthetic Rashba spin–orbit system using a silicon metal-oxide semiconductor

Abstract

The spin-orbit interaction (SOI), as a manifestation of a relativistic effect in solids, has been attracting great attention in condensed matter physics because of its abundant nature for manipulating and/or converting a spin degree of freedom. Compound materials with bulk inversion symmetry breaking (GaAs, BiTeI, NbSe 2 …), heterostructures consisting of the aforementioned materials (InGaAs/InAlAs, Bi/Ag…) and single heavy elements (Pt, W, Ta, Bi…) are pivotal material systems for generating strong Dresselhaus-and Rashba-type SOI and for shedding light on a wide variety of modern physics such as two-dimensional materials science, superconductivity, magnetoelectrics, spintronics etc. Consequently, however, light elements and materials with bulk inversion symmetry have been outside the scope of the quest for SOI in solids. In this work, we show that a Si metal-oxidesemiconductor (MOS) is a new material stage possessing Rashba-type SOI, although Si is a light element and has lattice inversion symmetry resulting in inherently negligible SOI in bulk form. A strong gate electric field is applied to the Si MOS, and unexpectedly, we observe spin precession of propagating spins in the Si through the formation of an emergent effective magnetic field due to the SOI in the Si MOS. Furthermore, the Rashba parameter  in the system increases linearly up to 9.8×10 −16 eV•m for a gate electric field of 0.5 V/nm, i.e., it is gate tuneable, and the spin splitting  0 (= 0.6 eV) is equivalent to that in strained GaAs. This finding is a successful establishment of a synthetic Rashba system using a ubiquitous light element with bulk inversion symmetry and pioneers a new family of SOI systems.The SOI gives rise to a wide variety of fruitful condensed matter physics, and it has been playing a central role in a wide variety of physical phenomena such as spin manipulation without magnetic fields 1,2 , ordinal and inverse spin Hall effects enabling spin conversion 3-7 , the spingalvanic effect and its inverse effect 8,9 , giant spin splitting at an interface and in bulk 10,11 and Ising Cooper-pairing superconductivity 12 . Breaking the bulk inversion symmetry and/or

Geometric Origin of Intrinsic Spin Hall Effect in an Inhomogeneous Electric Field

“…There are many materials, whose electronic structures are descried by the Rashba or Dresselhaus model, such as (i) 2D interfaces of InAlAs/InGaAs [43] and LaAlO 3 /SrTiO 3 [44], (ii) Si metal-oxide-semiconductor (MOS) heterostructure [45], and (iii) surfaces of heavy materials like Au [46] and BiAg(111) [47,48]. By using the well-known experimental techniques probing intrinsic spin Hall effect [4,7,9,49,50], we expect to detect the intriguing Fermi level-dependence of the q 2 -term of the SHC under the spatially modulating electric field by tuning its wavelength.…”

All‐Electric Spin Device Operation Using the Weyl Semimetal, WTe2, at Room Temperature

“…Local symmetry breaking in a wide variety of material systems has allowed the creation of an emergent effective magnetic field in GaAs, [ 32 ] Bi/Ag, [ 33 ] bilayer graphene, [ 34,35 ] van der Waals heterostructures, [ 36,37 ] and Si/SiO 2 . [ 38 ] The results presented here enable Weyl semimetals to join a new family of intriguing material systems allowing spin creation, propagation and extraction like those materials systems described above. Furthermore, creation of an all‐electric spin device made of a TQM allowing quite fast carrier motion due to the Dirac‐like linear bands and its operation at room temperature can pave a new pathway for novel and robust spin devices resilient to thermal fluctuation.…”

Research on Spintronic Functions of Non-Metallic Materials and Its Modulation by External Fields

“…14) 94) . Furthermore, significant achievements in basic physics viewpoints are spinpumping-induced spin transport in p-type Si 95) and electric field modulation of spin precession (spin manipulation without an external magnetic field) due to synthetic Rashba field in Si/SiO2 96) . Especially, spin manipulation by the gate electric field in Si spin FET shown in Fig.…”