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arXiv 1107.3480cond-mat.mes-hallphysics.plasm-ph
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用微波激发二维缺陷电子气中的等离子体:尾场方法

Excitation of plasmons in two-dimensional electron gas with defects by microwaves: Wake-field method

Eduard Takhtamirov, Roderick V. N. Melnik

摘要:

我们发展了一种分析方法来寻找微波产生的等离子体在二维电子气的缺陷。用等离子体中运动的带电粒子的尾流场来表示激发。结果明确地解决了光子到等离子体激元转换的效率和激发的类型。虽然在较大的等离子体波数下达到激发对辐射的强吸收,但在最佳波数下产生强烈的持续等离子体波。后一种波数取决于等离子体激元的光谱和波需要行进而基本上不衰减的距离。它们的类型,可以是移动的或站立的,由缺陷的几何形状和辐射的偏振决定。我们确定这种类型的旅行等离子体作为圆形等离子体激元,激发点缺陷,和横向等离子体激元,激发直线缺陷和旅行远离(朝向)的电线,如果他们的群速度是正(负)。非线性激励也占。特别是,我们分析了零次谐波,线性的微波强度,它具有冻结的电荷密度波的字符。从缺陷排列在截断周期集的基本尾流的干扰可以产生放大的等离子体激元,这是很容易描绘。

英文摘要:

We develop an analytical method to find plasmons generated by microwaves in a two-dimensional electron gas with defects. The excitations are expressed in terms of the wake field of a charged particle moving in plasma. The result explicitly addresses the efficiency of the photon-to-plasmon conversion and the type of excitation. While strong absorption of the radiation by the excitations is reached at larger plasmon wave numbers, intense persistent plasma waves are created at optimal ones. The latter wave numbers depend on the spectrum of plasmons and the distance that the waves are required to travel without being substantially attenuated. Their type, which can be traveling or standing, is governed by the geometry of the defects and the polarization of the radiation. We identify such types of traveling plasmons as circular plasmons, excited at dot defects, and traverse plasmons, excited at straight wire defects and traveling away from (toward) the wires if their group velocity is positive (negative). Nonlinear excitations are also accounted for. In particular, we analyze the zeroth harmonic, linear in the microwave intensity, which has the character of a frozen charge density wave. The interference of elementary wakes from defects arranged in truncated periodic sets can produce amplified plasmons, which are easily portrayed.

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