Heonjoon Park: Correlation-driven Topological Phase Diagram of Twisted MoTe2

Correlation-driven Topological Phase Diagram of Twisted MoTe2

Abstract: Twisting two layers of MoTe2 at small angles creates a moiré superlattice with flat, topologically nontrivial bands. In this system, strong electron interactions lead to spontaneous ferromagnetism, acting as an effective magnetic field. Recently, observations of fractionally quantized Hall resistance at certain fractional fillings of the moiré lattice, such as 2/3 and 3/5, have provided clear evidence for the fractional quantum anomalous Hall effect (FQAHE), characterized by fractional charge excitations in the absence of an external magnetic field. Here, we investigate the evolution of the correlated topological phases as a function of twist angles ranging from 2 to 5 degrees, revealing a complex landscape of fractional Chern insulators (FCIs), correlated insulator states, and exotic magnetic phases. Enhanced device quality enables us to detect electric-field and twist angle-driven topological phase transitions, along with additional fractional states. The direct observation of the FQAHE and related phases offer new insights into charge fractionalization and the behavior of Abelian anyons at zero magnetic field.

Bio: Heonjoon ‘Joon’ Park is a senior graduate student in Xiaodong Xu’s lab in the University of Washington. His research focuses on understanding strongly correlated phenomena and topology in two-dimensional moiré materials using transport and optical spectroscopy.