Dynamics of the electric current in an ideal electron gas: A sound mode inside the quasiparticles

The spin-orbit coupling provides a versatile tool to generate and to manipulate the spin degree of freedom in low-dimensional semiconductor structures. The spin Hall effect, where an electric current drives a transverse spin current and causes a nonequilibrium spin accumulation near the sample boundary,1,2 the spin-galvanic effect, where a nonequilibrium spin polarization drives an electric current3,4 or the reverse process, in which an electrical current generates a non-equilibrium spin-polarization,5–9 are all consequences of spin-orbit coupling. In order to observe a spin Hall effect a bias driven current is an essential prerequisite. Then spin separation is caused via spin-orbit coupling either by Mott scattering (extrinsic spin Hall effect) or by spin splitting of the band structure (intrinsic spin Hall effect). Recently an elementary effect causing spin separation which is fundamentally different from that of the spin Hall effect has been observed.10 In contrast to the spin Hall effect it does not require an electric current to flow: it is spin separation achieved by spin-dependent scattering of electrons in media with suitable symmetry. It is show that by free carrier (Drude) absorption of terahertz radiation spin separation is achieved in a wide range of temperatures from liquid helium temperature up to room temperature. Moreover the experimental results demonstrate that simple electron gas heating by any means is already sufficient to yield spin separation due to spin-dependent energy relaxation processes of non-equilibrium carriers. In order to demonstrate the existence of the spin separation due to asymmetric scattering the pure spin current was converted into an electric current. It is achieved by application of a magnetic field which polarizes spins. This is analogues to spin-dependent scattering in transport experiments: spin-dependent scattering in an unpolarized electron gas causes the extrinsic spin Hall effect, whereas in a spin-polarized electron gas a charge current, the anomalous Hall effect, can be observed. As both magnetic fields and gyrotropic mechanisms were used authors introduced the notation "magneto-gyrotropic photogalvanic effects" for this class of phenomena. The effect is observed in GaAs and InAs low dimensional structures at free-carrier absorption of terahertz radiation in a wide range of temperatures from liquid helium temperature up to room temperature. The results are well described by the phenomenological description based on the symmetry. Experimental and theoretical analysis evidences unumbiguously that the observed photocurrents are spin-dependent. Microscopic theory of this effect based on asymmetry of photoexcitation and relaxation processes are developed being in a good agreement with experimental data. Note from Publisher: This article contains the abstract only.

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Rectification of AC Electric Current at the Edge of 2D Electron Gas

physica status solidi (b) ◽

10.1002/pssb.202000291 ◽

2020 ◽

pp. 2000291

Author(s):

Mikhail V. Durnev ◽

Sergey A. Tarasenko

Keyword(s):

Electric Current ◽

Electron Gas ◽

2D Electron Gas

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Motion of Electron Gas and the Induced Nanofilm Electromigration

First International Conference on Integration and Commercialization of Micro and Nanosystems, Parts A and B ◽

10.1115/mnc2007-21150 ◽

2007 ◽

Author(s):

Bing-Yang Cao ◽

Qing-Guang Zhang ◽

Zeng-Yuan Guo

Keyword(s):

Kinetic Energy ◽

Electric Current ◽

Current Density ◽

Electron Gas ◽

Electric Current Density ◽

Electric Resistance ◽

Energy Effect ◽

Ohm’S Law ◽

Ohm's Law ◽

Electron Wind

Understanding how electron gas moves and induces electromigration is highly desirable in micro- and nano-electronic devices. Based on introducing some novel concepts of electron gas momentum, kinetic energy and resisting force, we establish the continuum, momentum and energy conservation equations of the electron gas in this paper. Through analyzing the control equations, the Ohm’s law can be derived if the inertial force or the kinetic energy of the electron gas is ignored. Thus, the Ohm’s law is no longer applicable if the variation of the electron gas momentum is too large to be ignored. For instance, the kinetic energy variation can not be ignored for the electron gas with a high velocity flowing along the conductor with variable cross-sections. Under such conditions, the electric resistance of the section-variable conductors is a function of the electric current density and direction, which is referred to as a kinetic energy effect on the electric resistance. Based on the control equations of the electron gas motion, the electron wind force and the kinetic energy can also be calculated. The kinetic energy transferred from the electron wind to metallic atoms increases greatly with the increasing electric current density. It may be comparable with the activated energy of the metallic atoms in nanofilms. Thus, the electromigration induced by the electron wind can be regarded as another kind of kinetic energy effect of the electron gas, i.e. kinetic energy effect on the electromigration.

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