Effects of in-plane magnetic fields on the electronic cyclotron effective mass and Landé factor in GaAs-(Ga,Al)As quantum wells

Abstract

The dependence of the electron Landé g-factor on carrier confinement in quantum wells recently gained both experimental and theoretical interest. The g factor of electrons in GaAs-(Ga,Al)As quantum wells is of special interest, as it changes its sign at a certain value of the well width. In the present work, the effects of an in-plane magnetic field on the cyclotron effective mass and on the Landé g ⊥ -factor in single GaAs-(Ga,Al)As quantum wells are studied. Theoretical calculations are performed in the framework of the effective-mass and nonparabolic-band approximations. The Ogg-McCombe Hamiltonian is used for the conduction-band electrons in the semiconductor heterostructure, and the Landé g ⊥ -factor theoretically evaluated is found in good agrement with available experimental measurements.Keywords: Magnetic fields; Quantum wells; g-factor; Cyclotron effective mass Semiconductor heterostructures, such as quantum wells (QWs), quantum-well wires (QWWs), quantum dots (QDs), and superlattices (SLs) have been widely studied in the past three decades. Such interest was motivated by possible electronic and opto-electronic applications and by the need to understand fundamental properties of matter at nanoscale dimensions. In that respect, the transport of spin-polarized electrons by using ferromagnetic probe tips in a low-temperature scanning tunnelling microscope opened up the possibility of investigating magnetic systems at spatial resolutions in the angstrom scale [1]. Of course, the ability to manipulate single spins [2] is one of the important aspects in the development of quantum information processing and spintronics. In particular, the dependence of the electronic effective mass and electron Landé g-factor on carrier quantum confinement in QWs and QDs has recently gained the community attention both experimentally as well as theoretically [3][4][5][6][7][8]. The g-factor of electrons in GaAs-Ga 1−x Al x As QWs is of special interest, as it changes its sign at certain values of the well width. In this study we are particularly interested in the experimental work by Hannak et al [4] who determined the electron Landé factor as a function of the GaAs-Ga 1−x Al x As well width from 1 to 20 nm under in-plane magnetic fields by the technique of spin quantum beats. We are also concerned with the experimental data by Le Jeune et al [5] who studied the anisotropy of the electron Landé factor in GaAs QWs, and by Malinowski and Harley [6] who investigated the influence of quantum confinement and built-in strain on conduction-electron g factors in GaAs/Al 0.35 Ga 0.65 As QWs and strained-layer In 0.11 Ga 0.89 As/GaAs QWs, for QW widths between 3 and 20 nm. Here, we are concerned with the effects of in-plane magnetic fields on the cyclotron effective mass and Landé g ⊥ -factor in GaAs-Ga 1−x Al x As semiconductor QWs, within the effective-mass and non-parabolic-band approximations [9,10], with theoretical results compared with available experimental measurements. Details of the present work will be presented elsewhere [1...