Interference effects induced by a precessing easy-plane magnet coupled to a helical edge state
Interference effects induced by a precessing easy-plane magnet coupled to a helical edge state
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DOI：
10.1103/physrevb.103.115142
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发表时间：
2020-12
期刊：
影响因子：
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通讯作者：
Kevin A. Madsen;P. Brouwer;P. Recher;P. Silvestrov
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文献类型：
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作者：
Kevin A. Madsen;P. Brouwer;P. Recher;P. Silvestrov
磁性绝缘体与二维拓扑绝缘体的螺旋电子边缘的相互作用已被证明会导致许多有趣的现象。其中之一是，对于磁各向异性轴的合适取向，与易平面磁体的交换耦合对通过螺旋边缘的DC电传输没有影响，尽管它在螺旋边缘的频谱中打开了间隙[Meng等人，物理学\修订版本\ B {\bf 90}，205403（2014）]。在这里，我们从理论上考虑这样一个磁铁嵌入在干涉仪，由一对螺旋边缘状态连接的两个隧道接触，电子可以隧道之间的两个边缘。使用散射矩阵的方法，我们表明，在干涉仪臂之一的磁铁的存在下，产生AC电流响应于所施加的直流电压。另一方面，DC Aharonov-Bohm效应在零温度和小DC电压下不存在，并且仅在所施加的电压或温度超过磁致激发间隙时出现。
The interaction of a magnetic insulator with the helical electronic edge of a two-dimensional topological insulator has been shown to lead to many interesting phenomena. One of these is that for a suitable orientation of the magnetic anisotropy axis, the exchange coupling to an easy-plane magnet has no effect on DC electrical transport through a helical edge, despite the fact that it opens a gap in the spectrum of the helical edge [Meng {\em et al.}, Phys.\ Rev.\ B {\bf 90}, 205403 (2014)]. Here, we theoretically consider such a magnet embedded in an interferometer, consisting of a pair of helical edge states connected by two tunneling contacts, at which electrons can tunnel between the two edges. Using a scattering matrix approach, we show that the presence of the magnet in one of the interferometer arms gives rise to AC currents in response to an applied DC voltage. On the other hand, the DC Aharonov-Bohm effect is absent at zero temperature and small DC voltages, and only appears if the applied voltage or the temperature exceeds the magnet-induced excitation gap.