Observation of Anisotropic Effects in Electron Transport in layered TiS₂ Single Crystals.

In this work we present our investigations on transition metal dichalcogenide - TiS₂ single crystals and show a detailed investigation of resistivity measurements performed in the current in-plane (CIP) and current perpendicular-to-plane (CPP) configurations. We observe a strong structural anisotropy (~10³) through resistivity measurements in the two configurations. The CIP resistivity varies as T³ at low temperatures (9 - 30 K), following Bloch - Wilson scattering. From 31 - 300 K, the temperature varies as T^1.6 and is attributed to strong coupling between electron and acoustic phonons. The CPP configuration shows similar behavior up to 200 K. However, the CPP resistivity diverges as T⁵ above 200 K up to room temperature which is highly interesting. We are able to induce exactly the same behavior in the CIP configuration through ion beam irradiation. We suggest that the T⁵ dependence in the CPP mode of pristine sample and CIP mode of irradiated sample is due to flexural phonons. This result is intriguing and opens up opportunities for further theoretical and experimental investigations on TiS₂.