Parabolic Quantum Well of Diluted Magnetic Semiconductor under Crossed Fields

Abstract

PACS: 73.21.Fg; 75.50.Pp We report on results of electronic features of parabolic quantum well (PQW) of diluted magnetic semiconductor (DMS) under crossed fields. The electric field is applied parallel to the growth direction and the magnetic field is transversal to this one. For specific values of the magnetic and electric fields the effective potential associated to the conduction band resembles a double quantum well (DQW). The barrier of the heterostructure is made of DMS, consequently the interaction between the localized spins with external magnetic field is considered. We show that in DQW configuration the wave function of this system is strongly dependent on the spin polarization. In this particular situation, the energy levels with different spin polarization can cross as the external field varies, this is interesting for tuning electromagnetic transitions in opto-electronic devices.Introduction During the last two decades, the field of semiconductor has undergone dramatic changes. Many new physical effects have been observed and put to practical use. Semiconductor compounds are widely used for high speed electronic devices as well as for opto-electronic devices and heterostructures based on them, specially those based on the GaAs/(Ga,Al)As system. However, the idea of exploring both, the charge and spin of an electron in the semiconductors and their heterostructures will enhance the performance of existing devices. Diluted magnetic semiconductor (DMS) is one of the best candidates to combine semiconductor electronics with magnetism. The study of DMS has been centered mostly on II-VI based DMS such as CdTe and ZnS, although, recently it was possible to grow [1] a new class of III-V based ferromagnetic semiconductor (Ga,Mn)As and its heterostructures by low temperature molecular beam epitaxy. The possibility of preparing these heterostructures with abrupt interfaces offers unique opportunities for studying spin-related phenomena in well controlled systems, including spin-related tunneling effects. In DMS the Landé factor is a function of the applied magnetic field, temperature and Mn molar fraction x. In these materials the g-factor can reach values much bigger than pure semiconductor, for example for low field values gðB ! 0Þ ¼ À1:46 in CdTe and gðB ! 0Þ ¼ þ100 in Cd 0:98 Mn 0:02 Te at helium temperatures [2]. For a fixed value of Mn concentration, the g-factor can not only vary the magnitude when the magnetic field is applied but also can change the sign, in other words, a non-zero magnetic field with vanishing g-factor is existing. The application of magnetic and electric fields on such devices can be a powerful tool, because these fields can confine or dislocate charged particles into these heterostructures. The parabolic