Ferroelectric Quantum Point Contact in Twisted Transition Metal Dichalcogenides
In twisted transition metal dichalcogenides (tTMDs), atomic reconstruction gives rise to moir\'e domains with alternating ferroelectric polarization, whose domain size and overall electric dipole moment are tunable by an out-of-plane electric field. Previous transport measurements in Hall bar devices have successfully demonstrated the overall ferroelectric behavior of tTMDs from a collective ensemble of ferroelectric moir\'e domains. To locally probe a single ferroelectric moir\'e domain, we fabricate and study mesoscopic quantum transport via a gate-defined twisted molybdenum disulfide (tMoS2) quantum point contact (QPC). The local property of a single moir\'e domain is invulnerable to long-range disorder and twist-angle inhomogeneity, resulting in an unusually long conductance plateau with large electrical hysteresis. The comparison between local and global measurements confirms that antiferroelectricity can emerge from alternating polarization of individual ferroelectric domains. Using a QPC as a single charge sensor, we characterize the nature and time scale of different domain evolution mechanisms with single atomic dipole resolution. Our findings shed new light on the microscopic ferroelectric behavior and dynamics within a single tTMD moir\'e domain, paving the way toward more advanced ferroelectric quantum devices with tunable local Hamiltonian, such as ferroelectric tTMD quantum dots (QDs).