Magnon transport through microwave pumping
Magnon transport through microwave pumping
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DOI：
10.1103/physrevb.92.014422
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发表时间：
2015-02
影响因子：
3.7
通讯作者：
Kouki Nakata;P. Simon;D. Loss
中科院分区：
文献类型：
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作者：
Kouki Nakata;P. Simon;D. Loss
提出了铁磁绝缘体中磁振子输运的微观理论。利用微波泵浦的磁振子注入，我们提出了一种产生磁振子直流电流的方法，并展示了如何增强混合铁磁绝缘结中磁振子直流电流的幅度。为此，专注于一个单一的FI，我们首先重新审视微波泵浦有限（室温）温度从微观角度的磁振子注入。接下来，我们将其应用到两种混合铁磁绝缘结。第一种是准平衡态的磁振子凝聚体与被微波抽运的磁振子之间的结，第二种是被抽运的磁振子与非凝聚态的磁振子之间的结。我们表明，准平衡磁振子凝聚产生交流和直流磁振子电流，而noncondensed磁振子产生基本上是直流磁振子电流。铁磁共振（FMR）极大地增加了泵浦磁振子的密度，并增强了这种磁振子电流。最后，使用微波泵浦在一个单一的FI，我们讨论的可能性，磁振子电流通过Aharonov-Casher相持续流动，即使在有限的温度。我们表明，这样的磁振子电流出现，即使在有限的温度下，在存在的磁振子-磁振子相互作用。由于FMR的存在，它的振幅变得比凝聚磁振子电流大得多。
We present a microscopic theory of magnon transport in ferromagnetic insulators (FIs). Using magnon injection through microwave pumping, we propose a way to generate magnon dc currents and show how to enhance their amplitudes in hybrid ferromagnetic insulating junctions. To this end, focusing on a single FI, we first revisit microwave pumping at finite (room) temperature from the microscopic viewpoint of magnon injection. Next, we apply it to two kinds of hybrid ferromagnetic insulating junctions. The first is the junction between a quasiequilibrium magnon condensate and magnons being pumped by microwave, while the second is the junction between such pumped magnons and noncondensed magnons. We show that quasiequilibrium magnon condensates generate ac and dc magnon currents, while noncondensed magnons produce essentially a dc magnon current. The ferromagnetic resonance (FMR) drastically increases the density of the pumped magnons and enhances such magnon currents. Lastly, using microwave pumping in a single FI, we discuss the possibility that a magnon current through an Aharonov-Casher phase flows persistently even at finite temperature. We show that such a magnon current arises even at finite temperature in the presence of magnon-magnon interactions. Due to FMR, its amplitude becomes much larger than the condensed magnon current.