Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea.
Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
Nat Commun. 2018 May 24;9(1):2052. doi: 10.1038/s41467-018-04474-4.
Quantum localization-delocalization of carriers are well described by either carrier-carrier interaction or disorder. When both effects come into play, however, a comprehensive understanding is not well established mainly due to complexity and sparse experimental data. Recently developed two-dimensional layered materials are ideal in describing such mesoscopic critical phenomena as they have both strong interactions and disorder. The transport in the insulating phase is well described by the soft Coulomb gap picture, which demonstrates the contribution of both interactions and disorder. Using this picture, we demonstrate the critical power law behavior of the localization length, supporting quantum criticality. We observe asymmetric critical exponents around the metal-insulator transition through temperature scaling analysis, which originates from poor screening in insulating regime and conversely strong screening in metallic regime due to free carriers. The effect of asymmetric scaling behavior is weakened in monolayer MoS due to a dominating disorder.
载流子的量子局域-离域可以用载流子-载流子相互作用或无序来很好地描述。然而，当这两种效应同时起作用时，由于复杂性和稀疏的实验数据，还没有很好地建立全面的理解。最近开发的二维层状材料在描述这种介观临界现象方面非常理想，因为它们既有强相互作用又有无序。绝缘相中的输运可以很好地用软库仑能隙图像来描述，该图像展示了相互作用和无序的贡献。利用该图像，我们证明了局域化长度的临界幂律行为，支持量子临界性。通过温度标度分析，我们观察到金属-绝缘转变周围的非对称临界指数，这源于绝缘相中的屏蔽不良以及相反的由于自由载流子在金属相中强烈的屏蔽。由于主导的无序，在单层 MoS 中，非对称标度行为的影响被削弱。
