Fermi surface topology and signature of surface Dirac nodes in LaBi

Abstract

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.

Magnetotransport properties and evidence of a topological insulating state in LaSbTe

“…The susceptibility (shown in the inset) exhibits a cusp at B = 0, as expected for a topological insulator [59]. Similar field dependence of magnetic susceptibility has been reported for several topological insulators such as Bi 2 Se 3 , Bi 2 Te 3 , Sb 2 Te 3 , Bi 1.5 Sb 0.5 Te 1.7 Se 1.3 [59][60][61] and narrow gap topological semimetals ZrTe 5 and LaBi [62,63], both with spin helical Dirac cone surface states. With temperature and chemical potential are set to zero, the total susceptibility can be mathematically formulated as [59],…”

Experimental observation of node-line-like surface states in LaBi

“…To date, the surface Dirac cones have already been extensively studied in topological insulators, such as the Bi 2 Se 3 family materials[21-23], while theoretical and experimental studies on the surface nodal lines are still rare [12].Recently, rare-earth monopnictide LaBi has been predicted to be a topological insulator based on firstprinciples calculations [24]. Moreover, magneto-transport measurements showed that LaBi hosts extremely large magnetoresistence (XMR) [25][26][27], in analogy to some topological semimetals, such as Cd 3 As 2 [28, 29], TaAs[30], and ZrSiS[31, 32]. These results have stimulated great research interest to search for the Dirac bands in LaBi.…”

The de Haas–van Alphen Effect Study of the Fermi Surface of LaBi

“…A value of n =1.8 is extracted from the fit, which is near to the quadratic field dependence of the MR, indicating a three dimensional charge carrier transport in LaBi. MR at low temperatures shows a non-saturating linear character which reaches to an extremely large value of 3.25 x 10 5 % at 2 K. This value of MR is nearly one order of magnitude higher than the values reported previously [11,12]. Figure 2, shows temperature dependent magnetization data in the magnetic field applied along c-axis.…”