Non-Kondo zero-bias anomaly in quantum wires

It has been suggested that a zero-bias conductance peak in quantum wires signifies the presence of Kondo spin-correlations, which might also relate to an intriguing one-dimensional (1D) spin effect known as the 0.7 structure. These zero-bias anomalies (ZBA) are strongly temperature dependent, and have been observed to split into two peaks in magnetic field, both signatures of Kondo correlations in quantum dots. We present data in which ZBAs in general do not split as magnetic field is increased up to 10 T. A few of our ZBAs split in magnetic field but by significantly less than the Kondo splitting value, and evolve back to a single peak upon moving the 1D constriction laterally. The ZBA therefore does not appear to have a Kondo origin, and instead we propose a simple phenomenological model to reproduce the ZBA which is in agreement mostly with observed characteristics.

有人提出，量子线中的零偏压电导峰意味着近藤自旋关联的存在，这可能也与一种有趣的一维（1D）自旋效应（称为0.7结构）有关。这些零偏压异常（ZBA）强烈依赖于温度，并且已观察到在磁场中分裂为两个峰，这两者都是量子点中近藤关联的特征。我们给出的数据表明，一般来说，当磁场增加到10 T时，ZBA不会分裂。我们的一些ZBA在磁场中会分裂，但分裂程度明显小于近藤分裂值，并且当横向移动一维收缩区时又变回单峰。因此，ZBA似乎并非源于近藤效应，相反，我们提出了一个简单的唯象模型来重现ZBA，该模型与观察到的特征大体一致。