Magnetoelectric Effect in Type-II Quantum Cone Induced by Donor Impurity

L F Garcia,J Sierra-Ortega,I D Mikhailov

doi:10.1155/2016/4961714

L F Garcia, J Sierra-Ortega + Show 1 more

Open Access

https://doi.org/10.1155/2016/4961714

Copy DOI

Abstract

We consider a model of donor centered at the base of a type-II nanocone, in which the excessive electron, released from the donor, is located within a narrow tube-shaped shell exterior region around the cone lateral surface. By solving the one-electron Schrödinger equation we analyze the alteration of the spatial probability distribution of the electron, the period of the Aharonov-Bohm oscillations of the energy levels, and the electric and magnetic moments induced by external electric and magnetic fields, applied along the symmetry axis. We show that the diamagnetic confinement provided by the magnetic field forces the electron to climb along the cone’s border, inducing the electric polarization of the structure. Similarly, the external electric field, which pushes the electron toward cone’s bottom, changes the order of the energy levels with different magnetic momenta varying the magnetic polarization of the structure. Our theoretical analysis reveals a new possibility for the coupling between the polarization and magnetization arising from the quantum-size effect in type-II semiconductor nanocones.

Highlights

The magnetoelectric effect is the phenomenon of inducing magnetic polarization by applying an external electric field that has been revealed previously in ceramics, crystals, and epitaxial crystalline layers, composites of piezoelectric and magnetostrictive particles in laminated layers [1]
The centrifugal force pushes the maxima of the electron distributions with different angular momenta toward the cone’s bottom, while the diamagnetic force drives them to the cone top
When the magnetic field is increased, the peaks of the electron distributions corresponding to different angular momenta begin to climb successively one by one from the bottom toward the top in the order of ascending angular momenta pushed up by the diamagnetic force

Summary

Introduction

The magnetoelectric effect is the phenomenon of inducing magnetic (electric) polarization by applying an external electric (magnetic) field that has been revealed previously in ceramics, crystals, and epitaxial crystalline layers, composites of piezoelectric and magnetostrictive particles in laminated layers [1]. The possibility of controlling magnetization and/or polarization by an electric field and/or magnetic field allows an additional degree of freedom in device design [2]. A reduced dimensionality that retains a single conducting channel in quasi-1D structures makes them very sensible to the external electric field with respect of any process related to the separation of positive and negative charges. The charge separation in a nanostructure can be reinforced by a type-II heterojunction, constructed from two materials for which both the edges of the valence and conduction bands of one component are lower than those in the other component. Nanowires with type-II heterojunctions core/shell like ZnO/ZnSe have been synthesized for solar cell applications [5], in which the hole states are more confined in the cylindrical core component and the electron states are more confined in the tube-shaped shell component. Radii of the core of ZnO nanowires are typically 60–120 nm and thickness of ZnSe shell is 5–8 nm [5]

Objectives

Results

Conclusion