Quasi-One-Dimensional Ta<sub>2</sub>PdSe<sub>6</sub> with Strong Topological Surface States for High-Performance and Polarization-Sensitive Terahertz Detection.

Yang, Liu; Wang, Dong; Hu, Zhen; Dong, Zhuo; Zhang, Yan; Tang, Keqin; Wang, Pengdong; Zhang, Junrong et al. · Nano Lett · 2025

basic_science · Level V

Where this comes from

Abstract

Topological surface states (TSS) in certain low-dimensional materials impart gapless band structure, massless quasiparticles, and nonlinear optical behavior, enabling distinct advantages for applications in low-energy photon detection. Herein, we develop a quasi-one-dimensional (quasi-1D) transition metal chalcogenide material, Ta<sub>2</sub>PdSe<sub>6</sub>, with robust TSS, which exhibits a gapless band structure protected by spin-momentum locking and time-reversal symmetry, alongside exceptional transport properties, including a high carrier mobility exceeding 10<sup>4</sup> cm<sup>2</sup>·V<sup>-1</sup>·s<sup>-1</sup>. The quasi-1D chain-like structure induces pronounced anisotropy and significantly reduces carrier scattering, further enhancing transport efficiency. Benefiting from these unique characteristics, the Ta<sub>2</sub>PdSe<sub>6</sub>-based terahertz (THz) detectors demonstrate outstanding performance with responsivity exceeding 3.63 A·W<sup>-1</sup>, a noise equivalent power of 7.4 pW·Hz<sup>-1/2</sup> at 0.28 THz, ultrafast response speed of 1.15 μs, and an exceptional photocurrent anisotropic ratio of 68.3. These findings highlight the significant potential of strong TSS in emerging materials to achieve high-performance and multifunctional THz detection.