Current patterns and orbital magnetism in mesoscopic dc transport.
Current patterns and orbital magnetism in mesoscopic dc transport.
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介观直流输运中的电流模式和轨道磁性
DOI：
10.1103/physrevlett.113.136602
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发表时间：
2014
影响因子：
8.6
通讯作者：
F. Evers
中科院分区：
文献类型：
--
作者：
M. Walz;J.Wilhelm;F. Evers
我们给出了在直流输运测量中出现的局域电流密度的初始计算。我们在局部电流密度中发现了明显的模式，即环电流(“涡流”)，它伴随着轨道的磁性。重要的是，环电流的大小可以超过(平均)传输电流几个数量级。我们发现相关的磁场表现出剧烈的波动，随着磁场梯度的达到。讨论了我们的观测结果与有机半导体等自旋-轨道相互作用很弱的系统中自旋弛豫的相关性。在这样的系统中，由偏置驱动的轨道磁引起的自旋弛豫与由超精细相互作用引起的自旋弛豫竞争，似乎具有相似的强度。我们提出了一种在直流电流存在下的核磁共振实验来观察感应磁场的空间涨落。
We presentab initiocalculations of the local current densityas it arises in dc-transport measurements. We discover pronounced patterns in the local current density, ring currents (“eddies”), that go along with orbital magnetism. Importantly, the magnitude of the ring currents can exceed the (average) transport current by orders of magnitude. We find associated magnetic fields that exhibit drastic fluctuations with field gradients reaching. The relevance of our observations for spin relaxation in systems with very weak spin-orbit interaction, such as organic semiconductors, is discussed. In such systems, spin relaxation induced by bias driven orbital magnetism competes with relaxation induced by the hyperfine interaction and appears to be of similar strength. We propose a NMR-type experiment in the presence of dc-current flow to observe the spatial fluctuations of the induced magnetic fields.