Pair spin–orbit interaction in low-dimensional electron systems

Abstract

The pair spin-orbit interaction (PSOI) is the spin-orbit component of the electron-electron interaction that originates from the Coulomb fields of the electrons. This relativistic component, which has been commonly assumed small in the low-energy approximation, appears large and very significant in materials with the strong SOI. The PSOI, being determined by the spins and momenta of electrons, has highly unusual properties among which of most interest is the mutual attraction of the electrons in certain spin configurations. We review the nature of the PSOI in solids and its manifestations in low-dimensional systems that have been studied to date. The specific results depend on the configuration of the Coulomb fields in a particular structure. The main actual structures are considered: one-dimensional quantum wires and two-dimensional layers, both suspended and placed in various dielectric media, as well as in the presence of a metallic gate. We discuss the possible types of the two-electron bound states, the conditions of their formation, their spectra together with the spin and orbital structure. In a many-particle system, the PSOI breaks the spin-charge separation as a result of which spin and charge degrees of freedom are mixed in the collective excitations.At sufficiently strong PSOI, one of the collective modes softens. This signals of the instability, which eventually leads to the reconstruction of the homogeneous state of the system. arXiv:1905.06340v2 [cond-mat.str-el] 8 Jul 2019 Pair spin-orbit interaction in solidsElectrons in solids form a fruitful ground to raise many ideas born in relativistic quantum theory and to give life to plenty of unexpected phenomena arising from the realization of electron states and band spectra that only recently appeared truly exotic. is became possible largely due to the discovery of new materials and technological advances in nanostructures.Just recall the discovery of graphene [14] and carbon nanotubes [15], topological insulators [16][17][18], Weyl and Dirac semi-metals [19], 2D transition metal dichalcogenides [20], and many more. e wide variety of non-trivial electronic states and spectra is due to the presence of the crystal. Electron motion in the crystal potential is generally speaking described by the relativistic Dirac equation [21], but in practice a quasi-relativistic approximation based on a small ratio /c of the electron velocity to the speed of light is su cient to describe the electronic spectrum of any material. Such an approximation is successful, in particular, in describing the behavior of electron spins, which has opened a whole new land of spin phenomena in solids [22].

Improved effective equation for the Rashba spin-orbit coupling in semiconductor nanowires

“…It is thus possible to significantly increase the wire's doping with a small gate voltage. The origin of the SO coupling in this setup is the inhomogeneous distribution of the charge along the radius of the wire, which is sometimes called pair SO coupling in the literature [78]. In the right pane, we can see that the red curve is in good agreement with the experimental data, whereas the blue one deviates, especially at large V gate , due to the large electrostatic potentials involved.…”

Bound Electron Pairs Formed by the Spin–Orbit Interaction in 2D Gated Structures

“…can essentially affect the dynamics of interacting electrons and result in new collective states. The pair SOI (PSOI) produced by the Coulomb fields Eðr i À r j Þ of interacting electrons has the following form [3]…”

Двухканальный Электронный Транспорт В Подвешенных Квантовых Точечных Контактах С Боковыми Затворами

“…Усиление межэлектронного взаимодействия подтверждается экспериментами с подвешенными наноструктурами [7-10]. Кроме этого было показано, что электрон-электронное взаимодействие в тонких пленках может иметь качественные отличия, проявляющиеся в притяжении и спаривании электронов [11][12][13]. Особенностью подвешенных наноструктур является также отсутствие отвода тепла непосредственно через подложку и связанный с этим характер явлений теплопереноса [14,15].…”