Science

Control of persistent spin helix in 2D electron gas

Date: 

Wednesday, 4 December, 2019 -
11:00 to 12:00

Where: 

UNSW Old Main Building (K15), Ground Level, Room G59

Hosts: 

School of Physics

Type of event: 

Seminar

In 2D electron gas with linear in the wave vector spin-orbit interaction, the evolution of an inhomogeneous electron spin distribution leads to appearance of spatial spin density oscillations. This indicates that the spin waves with a non-zero wave vector possess the longest lifetime. The direction of such long-lived spin helix is determined by the anisotropy of the spin-orbit splitting. We demonstrate that the external in-plane magnetic or electric fields alter the spin diffusion pattern and can even switch the spin helix direction. The maps of spin diffusion measured with spatial and temporal resolutions for two orthogonal magnetic field orientations enable us to directly determine the Dresselhaus and Rashba spin-orbit constants. We also observe that the period of the spin helix is substantially modified when the pump power is increased, which indicates that the photocarriers can affect the spin-orbit constants.

References:

[1] A.V. Poshakinskiy and S.A. Tarasenko, Phys. Rev. B 92, 045308 (2015).

[2] S. Anghel, F. Passmann, A. Singh, C. Ruppert, A.V. Poshakinskiy, S.A. Tarasenko et al, Phys. Rev. B 97, 125410 (2018).

[3] F. Passmann, S. Anghel, T. Tischler, A.V. Poshakinskiy, S.A. Tarasenko et al, Phys. Rev. B 97, 201413(R) (2018).

[4] F. Passmann, S. Anghel, C. Ruppert, A. D. Bristow, A. V. Poshakinskiy, S. A. Tarasenko, and M. Betz, Semicond. Sci. Technol 34, 093002 (2019).

 

Biography: 

Alexander Poshakinskiy is a PostDoc researcher in the Sector of Theory of Quantum Coherent Phenomena in Solids at Ioffe Institute, St. Petersburg (Russia). His research interests lie in the fields of spin physics, excitonic effects in semiconductor structures, and resonant optomechanics.