半古典方法於自旋弛豫和自旋傳輸之應用

Abstract

自旋電子學（Spintronics）在近代物理中是如此活躍的一道學門，其提供豐富的素材來探究此自然世界和提供推進下一個電子世代之發展的舞臺。 本文主要涉及在自旋電子學中極其重要的自旋弛豫（spin relaxation，SR）和自旋傳輸（spin transport，ST）之課題。 本文以半古典方法（semiclassical method）來探討介觀系統（mesoscopic system）於自旋-迴旋交互作用（spin-orbit interaction）下的電子自旋行為。 半古典方法之應用乃是此文的關鍵所在。 應用此方法我們獲得許多有趣的結果,諸如：於各式的自旋-迴旋交互作用下的電子自旋弛豫和自旋傳輸的範型（pattern）,我們分別探討此範型於自旋-迴旋交互作用（即有效磁場，effective magnetic field）之配置（configuration）及其實際大小之作用下的情形；由自旋弛豫和自旋傳輸之範型得到規則系統（regular system）和混沌系統（chaotic system）的本質性差異；有效磁場的方均根（root-mean-square，RMS）和其配置之等值性（equivalence）；自旋弛豫時間（spin relaxation time，T1）和自旋去相時間（spin dephasing time，T2）於自旋弛豫例子下之探討；Rashba項（Rashba term）和Dresselhause一次項（Dresselhause linear term）的等值性；自旋弛豫和自旋傳輸衰竭之減緩（slow down）；自旋弛豫和自旋傳輸衰竭之遏止（stop）；自旋波形編輯器（Spin Waveform Editor，SWE）等等。

Spintronics the so much active research region in modern physics, offers the matter to explore the fundamental nature of the world and the possible application in next electronic generation. In this thesis we try to explore some aspects about spintronics, especially focus on spin relaxation (SR) and spin transport (ST) in mesoscopic systems under the spin-orbit coupling effect in terms of modern semiclassicsl approach. The semiclassical approach is the hinge of this thesis. Applying the semiclassical method in spin relaxation and spin transport we obtain some interesting results, e.g. spin relaxation and spin transport patterns under nine (or ten) kinds of different effective magnetic field Beff which deduced from D'yakonov-Perel' spin-orbit interaction mechanism (i.e. the Rashba term and Dresselhause term) treated from two kinds of points of view -- normalized and realistic mimic, intrinsic distinguishableness between regular and chaotic systems from the patterns of SR and ST, the equivalence between root-mean-square (RMS) of Beff and Beff configuration, revelation of spin relaxation time T1 (often called longitudinal or spin-lattice time) and spin dephasing time T2 (also called transverse or decoherence time) in spin relaxation, equivalence between Rashba term case and Dresselhause linear term case in SR and ST, slow down the spin relaxation and spin transport decay, creating cases of never relaxed and decayable in spin relaxation case and spin transport case, spin waveform editor (SWE), and so on.