Changes in electrical transport property of graphene caused by disorder correlation in charge density wave

Abstract

From the success of isolation for monolayer graphene in 2005, researches about two-dimensional material have begun to bloom. Starting from the original properties of graphene, people have been studying newly emerging properties of the combined system of various two-dimensional materials such as transition metal dichalcogenide (TMDC) and graphene in the form of van der Waals heterostructure. Meanwhile, people found that the long-range interactions can diffuse to the adjacent layer and induce new properties, which is called the proximity effect. The advantage of the proximity effect in van der Waals heterostructure is that the adjacent layer doesn’t disrupt the quality of another layer and only gives interesting physics. The proximity effects of superconductivity, ferromagnetism, and spin-orbit coupling in semiconductors and metals have been extensively studied. However, the properties of charge density wave (CDW) systems combined with monolayer graphene have not yet been investigated. In this dissertation, we incorporate the CDW properties of 1T-TaS2 into electronic transport in graphene for the first time. During the CDW phase transitions, anomalous transport behaviors were observed within the graphene, which are closely related to the formation of correlated charged disorder in 1T-TaS2. In particular, the commensurate CDW phase forms a periodic charge distribution with potential fluctuations, and thereby constitutes the correlated charged impurities, decreasing resistivity and enhancing carrier mobility in graphene. We expect that the demonstration of the CDW-graphene heterostructure system paves a way to control the temperature-dependent carrier mobility and resistivity of graphene and to develop novel functional electronic devices such as graphene-based sensors and memory devices.