Faculty of Physics and Astrophysics, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
Phys Rev Lett. 2014 Apr 11;112(14):146803. doi: 10.1103/PhysRevLett.112.146803. Epub 2014 Apr 10.
We study the weak antilocalization (WAL) effect in the magnetoresistance of narrow HgTe wires fabricated in quantum wells with normal and inverted band ordering. Measurements at different gate voltages indicate that the WAL is only weakly affected by Rashba spin-orbit splitting and persists when the Rashba splitting is about zero. The WAL amplitude in wires with normal band ordering is an order of magnitude smaller than for wires with an inverted band structure. These observations are attributed to the Dirac-like dispersion of the energy bands in HgTe quantum wells. From the magnetic-field and temperature dependencies we extract the dephasing lengths and band Berry phases. The weaker WAL for samples with a normal band structure can be explained by a nonuniversal Berry phase which always exceeds π, the characteristic value for gapless Dirac fermions.
我们研究了在具有正常和倒置能带序的量子阱中制备的窄 HgTe 线的磁阻中的弱反局域（WAL）效应。在不同栅极电压下的测量表明，WAL 仅受拉什巴自旋轨道分裂的弱影响，并且当拉什巴分裂约为零时，WAL 仍然存在。具有正常能带序的线中的 WAL 幅度比具有倒置能带结构的线小一个数量级。这些观察结果归因于 HgTe 量子阱中能带的类狄拉克色散。从磁场和温度依赖性中，我们提取了退相长度和能带 Berry 相。对于具有正常能带结构的样品，WAL 较弱可以通过非普遍的 Berry 相来解释，该 Berry 相总是超过π，这是无间隙狄拉克费米子的特征值。
