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The quasimetallic 1T′ phase 2D transition‐metal dichalcogenides (TMDs) consist of 1D zigzag metal chains stacked periodically along a single axis. This gives rise to its prominent physical properties which promises the onset of novel physical phenomena and applications. Here, the in‐plane electronic correlations are explored, and new mid‐infrared plasmon excitations in 1T′ phase monolayer WSe2 and MoS2 are observed using optical spectroscopies. Based on an extensive first‐principles study which analyzes the charge dynamics across multiple axes of the atomic‐layered systems, the collective charge excitations are found to disperse only along the direction perpendicular to the chains. Further analysis reveals that the interchain long‐range coupling is responsible for the coherent 1D charge dynamics and the spin–orbit coupling affects the plasmon frequency. Detailed investigation of these charge collective modes in 2D‐chained systems offers opportunities for novel device applications and has implications for the underlying mechanism that governs superconductivity in 2D TMD systems. [ABSTRACT FROM AUTHOR]

2D transition metal dichalcogenides (2D‐TMDs) and their unique polymorphic features such as the semiconducting 1H and quasi‐metallic 1T′ phases exhibit intriguing optical and electronic properties, which can be used in novel electronic and photonic device applications. With the favorable quasi‐metallic nature of 1T′‐phase 2D‐TMDs, the 1H‐to‐1T′ phase engineering processes are an immensely vital discipline exploited for novel device applications. Here, a high‐yield 1H‐to‐1T′ phase transition of monolayer‐MoS2 on Cu and monolayer‐WSe2 on Au via an annealing‐based process is reported. A comprehensive experimental and first‐principles study is performed to unravel the underlying mechanism and derive the general trends for the high‐yield phase transition process of 2D‐TMDs on metallic substrates. While each 2D‐TMD possesses different intrinsic 1H‐1T′ energy barriers, the option of metallic substrates with higher chemical reactivity plays a significantly pivotal role in enhancing the 1H‐1T′ phase transition yield. The yield increase is achieved via the enhancement of the interfacial hybridizations by the means of increased interfacial binding energy, larger charge transfer, shorter interfacial spacing, and weaker bond strength. Fundamentally, this study opens up the field of 2D‐TMD/metal‐like systems to further scientific investigation and research, thereby creating new possibilities for 2D‐TMDs‐based device applications. The general trends for the high‐yield phase transition process of 2D‐transition metal dichalcogenides (TMDs) on metallic substrates are derived. While each 2D‐TMD possesses different intrinsic 1H‐1T′ energy barriers, the use of a metallic substrate with higher chemical reactivity plays a more pivotal role in increasing the 1H‐1T′ phase transition yield which is brought about via the enhancement of the interfacial hybridizations. [ABSTRACT FROM AUTHOR]

In article number 1802093, Wenjing Zhang, Andrivo Rusydi, Andrew T. S. Wee, and co‐workers derive the general trends for the high‐yield phase‐transition‐process of two‐dimensional transition metal dichalcogenides (2D‐TMDs) on metals (Au, Ag, Cu). While each 2D‐TMD possesses different intrinsic 1H‐1T' energy barriers, the use of a metallic substrate with higher chemical reactivity plays a more pivotal role in increasing the 1H‐1T' phase‐transition yield which is brought about via the enhancement of the interfacial hybridizations. [ABSTRACT FROM AUTHOR]