Topological Dirac states in a layered telluride TaPdTe5 with quasi-one-dimensional PdTe2 chains

We report the synthesis and systematic studies of a new layered ternary telluride ${\mathrm{TaPdTe}}_{5}$ with quasi-one-dimensional ${\mathrm{PdTe}}_{2}$ chains. This compound crystalizes in a layered orthorhombic structure with space group $Cmcm$. Analysis of its curved field-dependent Hall resistivity, using the two-band model, indicates the hole-dominated transport with a high mobility ${\ensuremath{\mu}}_{h}=2.38\ifmmode\times\else\texttimes\fi{}{10}^{3}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{2}\phantom{\rule{0.16em}{0ex}}{\mathrm{V}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$ at low temperatures. The in-plane magnetoresistance (MR) displays significant anisotropy with field applied along the crystallographic $b$ axis. The MR with the current applied along the $c$ axis is also measured in high magnetic fields up to 51.7 T. Remarkably, it follows a power-law dependence and reaches $(9.5\ifmmode\times\else\texttimes\fi{}{10}^{3})%$ at 2.1 K without any signature of saturation. The de Haas--van Alphen oscillations show a small Fermi surface pocket with a nontrivial Berry phase. The Shubnikov--de Haas (SdH) oscillations are detected at low temperatures and under magnetic fields above 28.5 T. Two effective masses ${m}^{*}$ ($0.26{m}_{e}$ and $0.41{m}_{e}$) are extracted from the oscillatory SdH data. Our first-principles calculations unveil a topological Dirac cone in its surface states, and, in particular, the topological index indicates that ${\mathrm{TaPdTe}}_{5}$ is a topologically nontrivial material.