Quantum Well Resonant Tunneling Diode Probe of Correlated States in Twisted Bilayer MoS${}_2$

Abstract

Moiré superlattices formed in transition metal dichalcogenides (TMDs) offer a versatile platform for exploring emergent quantum phases arising from strong electronic correlations. In this work, we develop a new experimental platform, the quantum well resonant tunneling diode (QWRTD), to probe the electronic landscape of $\approx 56.1^{\circ }$ twisted bilayer MoS${}_2$ (tMoS${}_2$). By measuring the differential conductance ($dI/d{V}_{\text{Probe}}$) as a function of filling factor $\nu$ and displacement field $D$, we observe a robust integer insulating feature at $\nu =1$ that persists across the measured displacement field range. Furthermore, we identify a displacement-field-induced fractional insulating feature near $\nu =3/4$ for $D<-75$~mV/nm. Its temperature dependence is consistent with a generalized Wigner crystal interpretation, although the microscopic order remains to be established. These features are also observed in another device with a similar twist angle ($\approx 56.4^{\circ }$). Our results provide evidence of correlated states in near-AB-stacked tMoS${}_2$ and establish QWRTD as a tool for investigating strong correlations in van der Waals heterostructures.