Magnetoswitching of current oscillations in dilute magnetic semiconductor nanostructures

R Escobedo,L L Bonilla,G Platero,M Carretero

doi:10.1103/physrevb.80.155202

Abstract

Strongly nonlinear transport through dilute magnetic semiconductor multiquantum wells occurs due to the interplay between confinement, Coulomb, and exchange interaction. Nonlinear effects include the appearance of spin-polarized stationary states and self-sustained current oscillations as possible stable states of the nanostructure, depending on its configuration and control parameters such as voltage bias and level splitting due to an external magnetic field. Oscillatory regions grow in size with well number and level splitting. A systematic analysis of the charge and spin response to voltage and magnetic field switching of II-VI dilute magnetic semiconductor multiquantum wells is carried out. The description of stationary and time-periodic spin-polarized states, the transitions between them and the responses to voltage or magnetic field switching have great importance due to the potential implementation of spintronic devices based on these nanostructures.

Highlights

Spin injection is one of the aims of spintronics1 thanks to the potential applications of injectors as spin light-emitting diode devices, etc
Nonlinear effects include the appearance of spin-polarized stationary states and self-sustained current oscillations as possible stable states of the nanostructure, depending on its configuration and control parameters such as voltage bias and level splitting due to an external magnetic field
Whether these dots are connected to the main oscillatory regions by extremely thin regionsnarrower than the discretization error of the codeis something our numerical solution of the model has not been able to decide

Summary

INTRODUCTION

Spin injection is one of the aims of spintronics thanks to the potential applications of injectors as spin light-emitting diode devices, etc. To tailor the properties of these spin oscillators or injectors, it is important to perform a systematic analysis of the transition from stationary to time dependent current, in terms of sample configuration, external magnetic field, doping density, etc. Large level splitting induced by B due to the exchange interaction provides DMS MQWSs with a new degree of freedom which is absent in conventional III-V weakly coupled n-doped semiconductor MQWSs.. Large level splitting induced by B due to the exchange interaction provides DMS MQWSs with a new degree of freedom which is absent in conventional III-V weakly coupled n-doped semiconductor MQWSs.15 Another important difference is that, in the latter, both charge dipoles and monopoles may be triggered at the injectordepending on its current-field characteristics: its conductivity if the relation between current and field is linearand both may cause SSCOs.. Where Ti is proportional to the transmission coefficient of the ith barrier. For electrons with spin Ϯ1 / 2, the chemical potential ␮iϮ and the electron densities niϮ are related by

The voltage bias condition can be written as

RESULTS

DISCUSSION