Ya-Ning Ren

Area of research

Materials Chemistry · Atomic and Molecular Physics, and Optics

Research interest

Research topics from publications: Orbital hybridization in graphene-based artificial atoms; Tunable Quantum Confinement in Individual Nanoscale Quantum Dots via Interfacial Engineering; Visualizing a single wavefront dislocation induced by orbital angular momentum in graphene; Realization of fractional-layer transition metal dichalcogenides; Realizing one-dimensional moiré chains with strong electron localization in two-dimensional twisted bilayer WSe 2. Representative work: Introducing quantum confinement has shown promise to enable control of charge carriers. Although recent advances make it possible to realize confinement from semiclassical regime to quantum regime, achieving control of electronic potentials in individual nanoscale quantum dots (QDs) has remained challenging. Here, we demonstrate the ability to tune quantum confined states in individual nanoscale graphene QDs, which are realized by inserting nanoscale monolayer WSe2 islands in graphene/WSe2 heterostructures via interfacial engineering. Our experiment indicates that scanning tunneling microscope (STM) tip pulses can trigger a local phase transition in the interfacial nanoscale WSe2 islands, wh Phase singularities are phase-indeterminate points where wave amplitudes are zero, which manifest as phase vertices or wavefront dislocations. In the realm of optical and electron beams, the phase singularity has been extensively explored, demonstrating a profound connection to orbital angular momentum. Direct local imaging of the impact of orbital angular momentum on phase singularities at the nanoscale, however, remains challenging. Here, we study the role of orbital angular momentum in phase singularities in graphene, particularly at the atomic level, through scanning tunneling microscopy and spectroscopy. Our experiments demonstrate that the scatterings between different orbital angular