Effect of symmetry reduction on the spin dynamics of (001)-oriented GaAs quantum wells

Abstract

Spin quantum beat spectroscopy is employed to investigate the in-plane anisotropy of the spin dynamics in (001) GaAs/AlGaAs quantum wells induced by an external electric field. This technique allows the anisotropy of the spin relaxation rate s and the electron Landé g factor g * to be measured simultaneously. The measurements are compared to similar data from (001) GaAs/AlGaAs quantum wells with applied shear strain and asymmetric barrier growth. All of these operations act to reduce the symmetry compared to that of a symmetric (001) quantum well in an identical manner (D 2d → C 2v ). However, by looking at the anisotropy of both s and g * simultaneously we show that the microscopic actions of these symmetry breaking operations are very different. The experiments attest that although symmetry arguments are a very useful tool to identify the allowed spin dependent properties of a material system, only a microscopic approach reveals if allowed anisotropies will manifest.

Impacts of Crystal Quality on Carrier Recombination and Spin Dynamics in (110)-Oriented GaAs/AlGaAs Multiple Quantum Wells at Room Temperature

“…Regarding the former, Karimov et al reported a calculation result that τ s is reduced to 1/30 by introducing an interface compositional gradient layer with the thickness of two monolayers [ 35 ]. In contrast, it is reported that the Rashba split energy that induces in-plane B eff is negligibly small for the MQW having compositional variations, which means that τ s is not modulated [ 36 , 37 ]. Since whether the compositional gradient layers are present or not is not sure in our samples, we do not mention their effects on τ s .…”

Symmetry-Induced Emergence of a Pseudo-Qutrit in the Dipolar Coupling of Two Qubits

“…The systematic search for symmetries and constants of motion exhibited by the Hamiltonian model is reported in Section 3 . A similar route has recently been used to investigate the dynamics of a pair [ 25 , 26 , 27 , 28 , 29 , 30 , 31 ] or a chain [ 32 , 33 ] of coupled spins (also greater than ) subjected to time-independent and time-dependent [ 34 , 35 , 36 ] external magnetic fields. Symmetry arguments have also been exploited to elegantly bring to light intriguing dynamic features of physical systems living in Hilbert spaces of infinite dimensions [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 ].…”

Asymmetric g Tensor in Low-Symmetry Two-Dimensional Hole Systems

“…[30][31][32][33][34] A reduction of the symmetry of the system leads to an anisotropic Zeeman splitting of electrons for different in-plane directions of B. [35][36][37][38][39] On the one hand, low-symmetry growth directions cause a slight anisotropy of the diagonal components g xx = g yy . 35 On the other hand, due to asymmetric band-edge profiles small off-diagonal components g xy = g yx = 0 arise while g xx = g yy .…”

“…35 On the other hand, due to asymmetric band-edge profiles small off-diagonal components g xy = g yx = 0 arise while g xx = g yy . [36][37][38][39][40] Remarkably, the g factor in spin-3/2 hole systems shows a strong dependence on the direction of B. The Zeeman splitting can differ by an order of magnitude for the in-plane and out-of-plane directions of B.…”