论文标题
空气稳定的Na3bi薄膜中的量子传输
Quantum Transport in Air-stable Na3Bi Thin Films
论文作者
论文摘要
Na3bi作为三维拓扑狄拉克半学和超薄形式引起了批量形式的重大兴趣，作为宽带二维拓扑绝缘子。它的极端空气敏感性有限于通过分子束外延到超高真空环境而生长的薄膜和超薄膜的实验努力。在这里，我们演示了用镁二氟化镁（MGF2）或硅（SI）盖层钝化的空气稳定Na3bi薄膜。电测量结果表明，在超高真空中，MGF2或Si的沉积对Na3bi的运输特性的影响很小。重要的是，与空气接触后的MGF2养育膜是空气稳定的，并且在暴露于空气后的100多小时保持金属，与瞬时降解相比，它们在未被活化的情况下保持了。空气稳定性使膜可以转移到常规的高磁场低温恒温器，从而实现了量子传输测量值，这些测量结果证明了空气暴露后Na3bi膜的狄拉克半学特征保留。
Na3Bi has attracted significant interest in both bulk form as a three-dimensional topological Dirac semimetal and in ultra-thin form as a wide-bandgap two-dimensional topological insulator. Its extreme air sensitivity has limited experimental efforts on thin- and ultra-thin films grown via molecular beam epitaxy to ultra-high vacuum environments. Here we demonstrate air-stable Na3Bi thin films passivated with magnesium difluoride (MgF2) or silicon (Si) capping layers. Electrical measurements show that deposition of MgF2 or Si has minimal impact on the transport properties of Na3Bi whilst in ultra-high vacuum. Importantly, the MgF2-passivated Na3Bi films are air-stable and remain metallic for over 100 hours after exposure to air, as compared to near instantaneous degradation when they are unpassivated. Air stability enables transfer of films to a conventional high-magnetic field cryostat, enabling quantum transport measurements which verify that the Dirac semimetal character of Na3Bi films is retained after air exposure.
