The anomalous magnetoresistance caused by the weak antilocalization (WAL) effects in 200-nm HgTe films is experimentally studied. This system is a high quality 3D topological insulator that has much stronger spatial separation of surface states compare to previously studied thinner HgTe structures. However, in contrast to that films, the system under study is characterized by a reduced strain resulting in an almost zero bulk energy gap. It has been shown that at all positions of the Fermi level the system exhibits a positive conductivity correction superimposed on classical parabolic magnetoresistance. Since high mobility of carriers, the analysis of the obtained results was performed using a ballistic WAL theory. The maximum of the WAL conductivity correction amplitude was found at a Fermi level position near the bulk energy gap indicating to full decoupling of the surface carriers in these conditions. The WAL amplitude monotonously decreases when the density of either bulk electrons or holes increases that is caused by the increasing coupling between surface and bulk carriers.

实验研究了在200nm HgTe薄膜中由弱抗局部化（WAL）效应引起的异常磁阻。该系统是高质量的3D拓扑绝缘体，与先前研究的更薄的HgTe结构相比，它具有更强的表面状态空间分离性。然而，与该膜相反，所研究的系统的特征在于减小的应变，导致几乎零的整体能隙。已经表明，在费米能级的所有位置上，系统都表现出叠加在经典抛物线型磁阻上的正电导率校正。由于载流子迁移率高，因此使用弹道WAL理论对获得的结果进行分析。在靠近本体能隙的费米能级位置处发现了WAL电导率校正幅度的最大值，表明在这些条件下表面载流子完全解耦。当体电子或空穴的密度增加时，WAL振幅单调降低，这是由于表面载流子与体载流子之间的耦合增加所致。