Proposed measurement of spin currents in a GaAs crystal using the electro-optical Pockels effect

Abstract

A new method for measuring spin currents is proposed, based on the linear electro-optic (Pockels) effect caused by the additional second-order nonlinear electric susceptibility (electro-optic tensor) generated by the spin currents. The non-zero elements of electro-optic tensor induced by spin currents in GaAs crystal are calculated, and the wave coupling theory of linear electro-optic effect is used to analyze the polarization change of a probe beam. The numerical results show that, for a linearly polarized probe beam with a frequency close to the band gap of GaAs crystal, its polarization rotation can be as large as 14 μrad under an applied electric field of about 350 V/mm. This effect should offer an alternative detection method for spintronics.

Influence of electrically induced refraction and absorption on the measurement of spin current by pockels effect in GaAs

“…It can be seen that the polarization of the output beam is elliptical, which is different from the result of Zhang et al 23 Based on Eq. (23), we can investigate the state of output light in detail.…”

“…Wang et al 22 also found that spin currents can induce second order optical Sum-Frequency generation which was verified by Werake and Zhao 1 to provide a method to detect spin currents. And very recently, Zhang et al 23 calculated the linear electro-optic coefficient induced by spin currents in GaAs and proposed to measure spin currents with Pockels effect.…”

Proposed manipulation of spin currents in GaAs crystal using the Pockels effect

“…According to Ref. 6, we set c = (1, 0, 0), a = (0, 1, 0) and b = (−1, 0, 0). For this configuration, using the initial conditions E 1 (0) 0 and E 2 (0) = 0, the solutions of Eq.…”

“…2, 3 Since it breaks the space inversion symmetry, the spin current could also induce second order nonlinear optical effects, such as second-harmonic generation 4,5 and linear electro-optic effect. 6 More recently, it has been shown that, in the spin current induced linear electro-optic effect in semiconductors, the polarization of incident light will be changed. 6 Basing on this, one could find that the spin angular momentum will exchange between the incident light and spin currents which could be utilized to change spin current.…”

“…6 More recently, it has been shown that, in the spin current induced linear electro-optic effect in semiconductors, the polarization of incident light will be changed. 6 Basing on this, one could find that the spin angular momentum will exchange between the incident light and spin currents which could be utilized to change spin current. In this paper, we propose a method to manipulate spin currents basing on Pockels effect, and the spin current manipulation in n-doped GaAs crystal is investigated with wave coupling theory of linear electro-optic effect 7 in particular.…”