Anisotropic Properties in Two-Dimensional Topological Insulator Candidates Ta₂M₃Te₅ (M = Pd, Ni)

In a two-dimensional topological insulator (2DTI), the insulating bulk band's nontrivial topology, protected by time-reversal symmetry, allows for creating unique, back scattering-free edge states. Therefore, the potential for 2DTI to be used in spintronics and quantum qubits is very promising. 2DTI has, however, only been validated in a few systems. Ta₂M₃Te₅ (M=Pd, Ni) has recently been proposed as a possible 2DTI candidate that can be modified by strain. Ta₂M₃Te₅ (M=Pd, Ni) also features an anisotropic in-plane crystal structure. This anisotropy may result in an anisotropic energy dispersion of phonons and electrons in momentum space. It may offer a foundation for the study of 1D physics. Here, we investigated Ta₂M₃Te₅ nanoflakes' anisotropic characteristics. EDS, XRD, TEM, and Raman were used to characterize the materials after they had been synthesized using chemical vapor transport. Using theoretical calculations and ultra-low frequency Raman spectroscopy, angle-dependent phonon vibrations have been investigated. The electrical transport properties of nanodevices made from a few atomic layers were studied.



Funding acknowledgment:

This work is supported by National Science Foundation (NSF) grant #1752997, and Louisiana Board of Regents (BOR) grant #LEQSF(2022-23)-ENH-DE-14, National Science Foundation (NSF) grant #1752997, Louisiana Board of Regents (BOR) grant #LEQSF(2022-23)-ENH-DE-14 and # LEQSF(2022-25)-RD-A-23, and the American Chemical Society Petroleum Research Fund.