半導體奈米元件的軌道與電子自旋磁性

Abstract

現代的半導體技術已經發展到可以製作人造半導體介觀物質，利用數十奈米尺度 的微小物體來建構這些新的介物質。而這些奈米半導體介物質讓我們很有潛能在 一個非常廣的範圍內操縱電磁場，這可以應用在很多新的應用元件或基礎科學， 短期可能的偉大成就包含：大規模量子計算、光學的負折射率介物質、使用非磁 性物質來產生靜磁性或動態磁性，等等驚人的發展。 明顯的，奈米半導體介物質需要一個合適的半導體奈米材料組成，近年來，量子 點、量子環、量子線、量子點分子的物理特性大幅被瞭解，包括他們的傳輸、磁 場還有光學行為，他們會是很合適的候選人。但是，我們對這些奈米材料相對應 的動態靜態的軌道與自旋的磁學卻所知不多。 在我們先前的工作，我們已經在理論上成功驗證了，在非磁性半導體上獲得特殊 動態靜態磁性的機會。我們也成功驗證了量子環複合材料足以產生等效負介電常 數與透磁率。 在這個接續的計畫中，我們設計發展一個有力的理論基礎去描述半導體奈米材料 與介物質的磁場控制行為。包含兩方面: 1. 擁有少數可控制的電子(電洞)能階的半導體奈米材料的軌道與自旋磁學的量 化描述 2. 在一個包含兩個以上的奈米材料的系統中，這些奈米材料間的量子與電磁交 互作用 我們將發展一套方法去設計並控制非磁性半導體奈米材料(包含量子點，量子 環，量子點分子)的軌道與自旋磁性，這將提供我們對半導體介物質特殊磁性的 最重要的資訊。我們強調，這個方法將有與傳統半導體科技相容的優勢。

Modern progress in semiconductor technology made it possible to fabricate artificial semiconductor meta-materials. Those new materials can be constructed from very small objects, typically a few tens of nanometers in size. Nano-structured semiconductor meta-materials potentially can manipulate electromagnetic fields in very wide diapason, which is particularly beneficial for many applications and devices, as well as for new basic science. The short list of possible urgent implementations in this field consists of realization of large scale quantum computation, meta-materials with the negative refracting index in optical range, static and dynamic artificial magnetism in basically non-magnetic materials, etc. Obviously, nano-structured semiconductor meta-materials should be developed and assembled on the base of appropriate semiconductor nano-objects. In recent years the knowledge of the physical properties of semiconductor nano-sized objects, like quantum dots, nano-rings, nano-wires, and quantum dot molecules, with respect to their transport, magnetic and optical behavior has increased considerably. Most of investigations in this domain focus upon the photo-luminescent, optical and transport properties. In the same time the corresponding knowledge about the dynamic and static orbital and spin magnetism of the semiconductor nano-objects is particularly weak. In our previous works we have demonstrated theoretically a wide range of opportunities to obtain unusual dynamic and static magnetic properties of nano-objects made from non-magnetic semiconductors. We also have demonstrated an opportunity to obtain simultaneously effective negative permittivity and permeability in optical range using composite materials made from nano-rings. In this project we plan to develop a robust theoretical basement to the existing knowledge about magnetically-controlled behavior of semiconductor nano-objects and meta-materials made from them. Two aspects have to obtain sufficient attention: - the proper quantitative description of the orbital and spin magnetism of semiconductor nano-objects with controllable few electron's (hole's) states, - the mutual quantum and electromagnetic interactions between semiconductor nano-objects for systems containing two (or more) nano-objects. We will develop methods for the design and controllability of orbital and spin magnetism in nano-objects (quantum dots, nano-rings, quantum dot molecules) made from non-magnetic semiconductor materials. This will provide us with the most important information relevant for the novel semiconductor meta-materials with unusual magnetic properties. We stress, that the semiconductor approach has the advantage of being compatible with conventional semiconductor technology.