  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.
