Investigation Of Transport Properties Of Layered Strongly Correlated Electronic Materials 1T-TaS₂

Layered transition metal chalcogenides are classic two-dimensional(2D)strong correlation electron systems.Due to their special lattice structures,these materials exhibit interesting physical and chemical properties:In some theoretical issues and practical applications,the chalcogenides have important research and application values.The 1T-Ta S₂ compounds studied in this thesis are one of the classic quarti-2D materials.They have non-linear conductivities at low temperatures,and the special prosperities of electrical pulse-driven reversible insulators.These works are helpful to the research of ultra-fast electrical switches,opening the way for the development of new electronic devices such as non-volatile memories.However,the microscopic conductive mechanism of 1T-Ta S₂ has not been clarified yet.In this thesis we study the electrical properties and micromechanics of 1T-Ta S₂ series compounds under the narrow pulses at low temperatures.The main research contents are as follows:1.By changing various parameters during sample preparation,such as temperature and duration time during chemical vapor transport,the synthesizing process has been optimized.The samples were characterized by X-ray diffraction and EDS.To determine that the samples we prepared were Ta S₂ series materials of the 1T phase.To expand the hysteresis temperature region of the material and the temperature region of the commensurate charge density waves phase,we doped Se in the preparation process.2.We use electric pulses with duration 40?s narrow pulses to excite 1T-Ta S₂specimens at different temperatures.Electrical pulses energetically induce originally ordered David hexagonal structure into a disordered one.The jump of the resistance at different temperatures and were recorded.further,we observe and analyze the effects of the pulses on the internal lattice structure of the samples.3.The slow relaxation of the resistance after the current pulse are observed,indicating that in the subsequent state process,the lattice structure slowly changes from disorder to a partially ordered state,possibly implying that the locally formed charge density waves domain textures gradually evolve to ordered patterns.