Peculiarities of electron transport and resistive switching in point contacts on TiSe₂, TiSeS, and Cu_xTiSe₂

Compound TiSe₂ has received much attention among the transition metal chalcogenides because of its thrilling physical properties concerning atypical resistivity behavior, the emergence of charge density wave (CDW) state, induced superconductivity, etc. Here, we report the discovery of a new feature of TiSe₂, namely, the observation of resistive switching in voltage biased point contacts (PCs) based on TiSe₂ and its derivatives doped by S and Cu (TiSeS, Cu_xTiSe₂). The switching occurs between a low resistive mainly “metallic-type” state and a high resistive “semiconducting-type” state when a bias voltage is applied (usually < 0.5 V), and reverse switching occurs when a voltage of opposite polarity is applied (usually < 0.5 V). The difference in resistance between these two states can reach up to two orders of magnitude at room temperature. The origin of this effect can be attributed to the variation of stoichiometry in the PC core due to the drift/displacement of Se/Ti vacancies under a high electric field. Additionally, we demonstrated that heating occurs in the PC core, which can facilitate the electric field-induced effect. At the same time, we did not find any evidence for CDW spectral features in our PC spectra for TiSe₂. The observed resistive switching allows proposing TiSe₂ and their derivatives as promising materials, e.g., for non-volatile resistive random access memory (ReRAM) engineering.