A research group led by Prof. HE Shaolong at the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences (CAS), has discovered a new low-dimensional topological Dirac semimetal, TaPtTe₅. The findings were published in Physical Review B. 

In recent years, the exploration of quantum materials with diverse symmetry-protected topological states has attracted great attentions in condensed matter physics, thanks to the unique physical properties such as unsaturated large magnetoresistance, negative magnetoresistance, charge carrier mobility, chiral anomalies, superconductivity, and quantum oscillations. Besides, topological materials showed potential applications in next-generation spintronics and quantum computing.  

The majority of topological materials identified thus far possess two-dimensional (2D) or three-dimensional (3D) structural characteristics. Prof. HE's group at NIMTE discovered a quasi-one-dimensional (quasi-1D) topological Dirac semimetal, TaPtTe₅. 

By virtue of the self-flux method, high-quality single crystals of a layered ternary telluride TaPtTe₅ was synthesized. The layered structure is composed of alternative PtTe₂ and TaTe₃ chains.

An anisotropic magnetoresistance and a nonlinear Hall effect at low temperatures were manifested in TaPtTe₅. Based on the analysis of the de Haas–van Alphen (dHvA) oscillations which were detected with the field applied along the normal-to-layer direction, the typical signatures of Dirac fermions were observed, indicating that TaPdTe₅ is a new topological material. The two light effective masses of charge carriers and corresponding nonzero Berry phases suggested the nontrivial band topology in TaPtTe₅, which was further verified with the first-principles calculations. 

The study revealed that TaPtTe₅ is another member among the quasi-1D topological semimetal family, including TaPdTe₅ and TaNiTe₅ which were also discovered by Prof. HE's group. 

Moreover, TaPtTe₅ showed weak van der Waals interlayer interaction and thus is an ideal platform for further research and applications of low-dimensional topological materials. The study may shed light on the exploration of topological superconductivity in this class of materials by chemical substitution, voltage gating, or high pressure, since that the ternary telluride Ta₄Pd₃Te₁₆ and Ta₃Pd₃Te₁₄ with similar structural characteristics are superconductors.