Spin Dynamics in the Second Subband of a Quasi Two Dimensional System Studied in a Single Barrier Heterostructure by Time Resolved Kerr Rotation

Abstract

By biasing a single barrier heterostructure with a 500nm-thick GaAs layer as the absorption layer, the spin dynamics for both of the first and second subband near the AlAs barrier are examined. We find that when simultaneously scanning the photon energy of both the probe and pump beams, a sign reversal of the Kerr rotation (KR) takes place as long as the probe photons break away the first subband and probe the second subband. This novel feature, while stemming from the exchange interaction, has been used to unambiguously distinguish the different spin dynamics ($T_2^{1\ast }$ and $T_2^{2\ast }$) for the first and second subbands under the different conditions by their KR signs (negative for $1^{st}$ and positive for $2^{nd}$). In the zero magnetic field, by scanning the wavelength towards the short wavelength, $T_2^{1\ast }$ decreases in accordance with the D'yakonov-Perel' (DP) spin decoherence mechanism. At 803nm, $T_2^{2\ast }$(450ps) becomes ten times longer than $T_2^{1\ast }$(50ps). However, the value of $T_2^{2\ast }$ at 803nm is roughly the same as the value of $T_2^{1\ast }$ at 815nm. A new feature has been disclosed at the wavelength of 811nm under the bias of -0.3V (807nm under the bias of -0.6V) that the spin coherence times ($T_2^{1\ast }$ and $T_2^{2\ast }$) and the effective $g^{\ast }$ factors ($|g^{\ast }(E1)|$ and $|g^{\ast }(E2)|$) all display a sudden change, due to the "resonant" spin exchange coupling between two spin opposite bands.

9pages, 3 figures

References in corpus (2)

• Effect of initial spin polarization on spin dephasing and electron g factor in a high-mobility two-dimensional electron system
• Multi-subband effect in spin dephasing in semiconductor quantum wells

Cited by in corpus (8)

• Spin dynamics in semiconductors
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• Electron spin relaxation in paramagnetic Ga(Mn)As quantum wells
• Long-lived nanosecond spin coherence in high-mobility 2DEGs confined in double and triple quantum wells
• Optical probing of spin dynamics of two-dimensional and bulk electrons in a GaAs/AlGaAs heterojunction system
• Tailoring multilayer quantum wells for spin devices
• Electron spin relaxation in $p$-type GaAs quantum wells
• Spin dynamics of electrons in the first excited subband of a high-mobility low-density 2D electron system