Spin nutation and polarization in ballistic semiconductor nanostructures

Abstract

The definitions of spin orientation and polarization vectors are introduced within the particle density matrix of scattering states in leads. It is shown that spin-density vector can be defined by the product of the spin orientation vector, being a unit direction vector, and the charge density, corresponding to the amplitude of the spin-density vector, experimentally observable by a spatial charge modulation measurement. When an electron transports through a ballistic semiconductor nanostructure, due to quantum interference of two spin eigenmodes, the electron spin generally undergoes nutation on its precession around the effective magnetic field resulting from spin-orbit interactions. The nutation of electron spin is found to be crucial for spin polarization in the quantum transport. When one of two spin-dependent channels in leads is evanescent, electron spin is shown to be fully polarized for distance from the interface larger than the spin precession length.

Broken mirror symmetry tuned topological transport in PbTe/SnTe heterostructures

“…More recently, LMR has been observed in numerous materials with gapless electronic states (e.g. graphene [29], topological insulators [30,31], Dirac and Weyl semimetals [32,33]). While there have been many theoretical models proposed to explain the LMR and no consensus is reached yet, the two most discussed models are Parish and Littlewood (PL)'s disorder induced mobility fluctuation model [34,35] and Abrikosov's quantum LMR model [36,37].…”

Viscous magnetoresistance of correlated electron liquids

“…Experimental support for the Stokes flow in electron transport has been reported in thin Potassium wires [7], and more recently in other metallic systems [8][9][10].Over the past few years, the role of momentumconserving scattering and hydrodynamic effects in electrical resistivity of low-dimensional systems was actively studied in the context of modern high mobility nanostructures. This includes equilibration effects in onedimensional wires [11][12][13][14][15], high mobility semiconductor heterostructures with strongly correlated carriers, such as p-and n-doped GaAs and SiGe quantum wells, as well as Si-MOSFETs [16,17], and graphene devices [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. In these systems electrons move in the presence of a smooth disorder potential with long range correlations.…”

Ballistic transport of bilayer graphene nanoribbons in a spatially modulated magnetic field

“…On the other hand, the carriers in bilayer graphene are massive fermions and will show no Klein tunneling. In addition, the occurrence of minimum conductivity of about e 2 =h in graphene is believed to be caused by the difficulty of confining the massless Dirac fermions [25]. There are published works on transmission through magnetic barriers in monolayer and bilayer graphene [26][27][28].…”