State Key Laboratory of Surface Physics and Department of Physics and ‡Collaborative Innovation Center of Advanced Microstructures, Fudan University , Shanghai 200433, China.
Nano Lett. 2015 Mar 11;15(3):2161-7. doi: 10.1021/acs.nanolett.5b00172. Epub 2015 Feb 25.
Recently, rock-salt IV-VI semiconductors, such as Pb(1-x)Sn(x)Se(Te) and SnTe, have been observed to host topological crystalline insulator (TCI) states. The nontrivial states have long been believed to exhibit ambipolar field effects and possess massive Dirac Fermions in two-dimension (2D) limit due to the surface hybridization. However, these exciting attributes of TCI remain previously inaccessible owing to the complicated control over composition and thickness. Here, we systematically investigate doping and thickness-induced topological phase transitions by electrical transport. We demonstrate the first evidence of the ambipolar properties in Pb(1-x)Sn(x)Se thin films. Surface gap opening is observed in 10 nm TCI originated from the strong finite-size effect. Importantly, magnetoconductance hosts a competition between weak antilocalization and weak localization, suggesting a strikingly tunable Berry phase evolution and strong electron-electron interaction. Our findings serve as a new probe to study electron behavior and pave the way for further exploring and manipulating this novel 2D TCI phase.
最近，岩盐 IV-VI 半导体，如 Pb(1-x)Sn(x)Se(Te) 和 SnTe，被观察到具有拓扑晶体绝缘体 (TCI) 态。由于表面杂化，这些非平凡态长期以来被认为具有双极性场效应，并在二维 (2D) 极限下具有大量的狄拉克费米子。然而，由于对成分和厚度的复杂控制，这些 TCI 的令人兴奋的特性仍然以前无法实现。在这里，我们通过电输运系统地研究了掺杂和厚度诱导的拓扑相变。我们在 Pb(1-x)Sn(x)Se 薄膜中首次证明了双极性特性的存在。在起源于强有限尺寸效应的 10nm TCI 中观察到表面能隙的打开。重要的是，磁导率在弱反局域和弱局域之间存在竞争，这表明 Berry 相演化具有显著的可调谐性和强电子-电子相互作用。我们的发现为研究电子行为提供了一个新的探针，并为进一步探索和操纵这种新型二维 TCI 相铺平了道路。
