Coulomb interaction effects in spin-polarized transport

Abstract

We study the effect of the electron-electron interaction on the transport of spin-polarized currents in metals and doped semiconductors in the diffusive regime. In addition to well-known screening effects, we identify two additional effects, which depend on many-body correlations and exchange and reduce the spin-diffusion constant. The first is the ''spin Coulomb drag''-an intrinsic friction mechanism which operates whenever the average velocities of up-spin and down-spin electrons differ. The second arises from the decrease in the longitudinal spin stiffness of an interacting electron gas relative to a noninteracting one. Both effects are studied in detail for both degenerate and nondegenerate carriers in metals and semiconductors, and various limiting cases are worked out analytically. The behavior of the spin-diffusion constant at and below a ferromagnetic transition temperature is also discussed.

Spin-Hall effect and spin-Coulomb drag in doped semiconductors

“…by renormalizing the skew scattering by a factor 1 + γ τ while leaving the side jump contribution to the spin conductivity unchanged. Therefore, except for the different scaling of γ with temperature the spin-Hall conductivity behaves very similarly in 2D and in 3D [68,69].…”

“…Returning to the Boltzmann approach, the electronelectron contribution to the collisional derivative has the form [68] …”

“…However, the situation looks quite different for electron-electron collisions: the collision of an up-spin electron with a down-spin electron leads to a momentum transfer that is preferentially oriented against the relative velocity of the two electrons (see figure 7) and is proportional to the latter. Taking the spin-flip relaxation time to be of the order of 500 ns (ten times larger than the spin-relaxation time in GaAs [84,85]) and the value of 1 γ of the order of the Drude scattering time, around 1 ps [68,69], and temperatures of the order of the Fermi energy T F ∼ 300 K we estimate that the spin-Coulomb drag contribution will dominate already for T ∼ 0.3 K. Further, for mobilities typical for semiconductors 10 4 -10 5 cm 2 V −1 s −1 the ratio of spin-Coulomb drag to the Drude resistivity can be as large as 10 (see more detailed discussion in section 4 and figure 9). …”

“…The spin-Coulomb drag [65][66][67][68][69][70][71] is a many-body effect arising from the interaction between electrons with opposite spins, which tends to suppress the relative motion of electrons with different spins and thus to reduce the spin diffusion constant. This effect has been recently observed in a (110) GaAs quantum well (which is essentially free of spin-orbit interaction) by Weber et al [72] by monitoring the time evolution of a spatially varying pattern of spin polarization, i.e.…”

Effect of the Coulomb interaction on spin injection in semiconductor structures

“…For TBT F the latter has a maximum that is comparable in value to the Drude resistivity [2], while for TtT F the spin susceptibility displays the maximum enhancement relative to its non-interacting value [2]. These two combined effects reduce the diffusion constant by as much as 50% [2]. Due to their dependence on D s the downstream and upstream spin diffusion lengths are strongly renormalized too (see Fig.…”