Circular dichroism inInAs∕GaAsquantum dots: Confinement-induced magnetism

Abstract

Self-assembled InAs/ GaAs quantum dots ͑QDs͒ are studied by means of circular polarization-resolved photoluminescence and pump-probe differential reflectivity as a function of the excitation density using a linear polarized pump laser. We observe an unexpected large circular polarization anisotropy, which decreases with increasing excitation density for both experimental techniques. Comparison of the respective polarization degrees reveals a ratio of approximately 0.2. Moreover, the reflection measurements reveal circular dichroism with a ratio of ⌰ + / ⌰ − = 1.16. Circular dichroism in semiconductor QDs can be explained by the induced magnetism as a result of light confinement in QDs, providing an anisotropic coupling between the pumpinduced QD exciton and the circularly polarized probe field.

Polarization-Sensitive Light Sensors Based on a Bulk Perovskite MAPbBr3 Single Crystal

“…In other words, there is a circular dichroism of PL. A circular dichroism ratio is determined by where and are the PL intensity of σ + and σ − circularly polarized lights with σ + light incidence [ 13 , 28 ]. The wavelength dependence of the circular dichroism ratio in Figure 4 b reveals that the circular dichroism ratio is increased basically with the wavelength increasing and appears maximal at values of ~540 and ~565 nm, which might be a result from the spin-orbit coupled recombination luminescence corresponding to the inner band and tail states, respectively, and the circular dichroism ratio can reach up to 9% for recombination luminescence due to the tail states at 565 nm.…”