Transport in Layered Ternary Transition-metal Tellurides Ta₂M₃Te₅ (M = Pd, Ni)

Two-dimensional topological insulator, also known as quantum spin Hall (QSH) insulator, exhibits novel one dimensional helical edge states at the boundaries. The robust conducting edge with forbidden back scattering is the consequence of the nontrivial topology of the insulating bulk band protected by time-reversal symmetry. Therefore, QSH insulators have great promise for potential application in spintronics. However, QSH state has been confirmed in limited systems. Recently, it was proposed that Ta₂M₃Te₅ are potential candidates for realizing the QSH effect, which is further tuned by strain. Also, the angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy measurements show a band gap at the Fermi level and topological edge states inside the gap of Ta₂Pd₃Te₅. Here, we report the transport study of Ta₂M₃Te₅ nanoflakes. The materials were synthesized by chemical vapor transport and characterized by EDS, XRD, TEM, and Raman. Nanodevices were fabricated for the transport measurement. The temperature-dependent resistivity of Ta₂Ni₃Te₅ shows the semiconductor properties with a small bandgap. The Hall effect and magnetoresistance have also been measured. The transport results show that Ta₂M₃Te₅ could be potential platforms for exploring QSH states.