Magnetic order in a frustrated two-dimensional atom lattice at a semiconductor surface
Magnetic order in a frustrated two-dimensional atom lattice at a semiconductor surface
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DOI：
10.1038/ncomms2617
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发表时间：
2013-03
影响因子：
16.6
通讯作者：
Gang Li;P. Höpfner;J. Schäfer;C. Blumenstein;S. Meyer;A. Bostwick;E. Rotenberg;R. Claessen;W. Hanke
中科院分区：
文献类型：
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作者：
Gang Li;P. Höpfner;J. Schäfer;C. Blumenstein;S. Meyer;A. Bostwick;E. Rotenberg;R. Claessen;W. Hanke
用于器件应用的二维电子系统可能会因为局部库仑排斥而失去其导电性能，从而导致Mott绝缘态。在三角形几何结构中，任何伴随的反铁磁自旋有序都可以通过几何挫折来防止，这会刺激人们对被称为自旋液体的“熔化”相的猜测。在这里，我们表明，对于通过外延原子在半导体上的吸附来实现三角电子系统，这种自旋无序并不出现。我们的研究将相关电子晶格的理论模拟得到的电子激发光谱与高分辨率光电子能谱数据进行了比较。我们发现，在光电子能谱中出现了一种不寻常的行状反铁磁自旋排列，这是由自旋图案引起的特征“阴影带”。在由非磁性成分组成的受挫晶格中，磁性有序是由于原子之间较远距离的电子跳跃而产生的。这一发现可以提供控制表面磁性的新方法。
Two-dimensional electron systems, as exploited for device applications, can lose their conducting properties because of local Coulomb repulsion, leading to a Mott-insulating state. In triangular geometries, any concomitant antiferromagnetic spin ordering can be prevented by geometric frustration, spurring speculations about ‘melted’ phases, known as spin liquid. Here we show that for a realization of a triangular electron system by epitaxial atom adsorption on a semiconductor, such spin disorder, however, does not appear. Our study compares the electron excitation spectra obtained from theoretical simulations of the correlated electron lattice with data from high-resolution photoemission. We find that an unusual row-wise antiferromagnetic spin alignment occurs that is reflected in the photoemission spectra as characteristic ‘shadow bands’ induced by the spin pattern. The magnetic order in a frustrated lattice of otherwise non-magnetic components emerges from longer-range electron hopping between the atoms. This finding can offer new ways of controlling magnetism on surfaces.