Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhannagar, Calcutta, 700 064, India.
Sci Rep. 2017 Jul 24;7(1):6321. doi: 10.1038/s41598-017-06697-9.
Novel topological state of matter is one of the rapidly growing fields in condensed matter physics research in recent times. While these materials are fascinating from the aspect of fundamental physics of relativistic particles, their exotic transport properties are equally compelling due to the potential technological applications. Extreme magnetoresistance and ultrahigh carrier mobility are two such major hallmarks of topological materials and often used as primary criteria for identifying new compounds belonging to this class. Recently, LaBi has emerged as a new system, which exhibits the above mentioned properties. However, the topological nature of its band structure remains unresolved. Here, using the magnetotransport and magnetization measurements, we have probed the bulk and surface states of LaBi. Similar to earlier reports, extremely large magnetoresistance and high carrier mobility have been observed with compensated electron and hole density. The Fermi surface properties have been analyzed from both Shubnikov-de Haas and de Haas-van Alphen oscillation techniques. In the magnetization measurement, a prominent paramagnetic singularity has been observed, which demonstrates the non-trivial nature of the surface states in LaBi. Our study unambiguously confirms that LaBi is a three-dimensional topological insulator with possible linear dispersion in the gapped bulk band structure.
新型拓扑物质是近年来凝聚态物理研究中迅速发展的领域之一。虽然这些材料从相对论粒子的基础物理角度来看非常有趣，但由于潜在的技术应用，它们奇异的输运性质同样引人注目。极端磁电阻和超高载流子迁移率是拓扑材料的两个主要特征，通常被用作识别属于此类的新化合物的主要标准。最近，LaBi 作为一个新系统出现，它表现出了上述特性。然而，其能带结构的拓扑性质仍未得到解决。在这里，我们使用磁输运和磁化测量来探测 LaBi 的体相和表面态。与早期的报告类似，在补偿电子和空穴密度下观察到了非常大的磁电阻和高载流子迁移率。费米面性质已经通过 Shubnikov-de Haas 和 de Haas-van Alphen 振荡技术进行了分析。在磁化测量中，观察到一个突出的顺磁奇异点，这证明了 LaBi 表面态的非平凡性质。我们的研究明确证实，LaBi 是一种具有可能在带隙体相带结构中呈线性分散的三维拓扑绝缘体。
