Location: BRIM 311

Time: 10:00 AM – 11:00 AM

Abstract: The tunability in the stacking of layered materials with van der Waals bonding provides a new and powerful approach to engineer their physical properties. Sliding ferroelectricity is one such example where an electric field drives one layer of materials to move relative to its neighbours due to an out-of-plane electric polarization arising from interlayer coupling. Sliding ferroelectricity can therefore occur in traditionally non-ferroelectric materials and has been observed in artificially stacked boron nitrides and transition metal dichalcogenides (TMDs). In this talk, I will show that such a hysteric phenomenon can occur in chemically synthesized rhombohedral molybdenum disulfide (3R-MoS2) crystals with pre-existing domain walls. I will first discuss our studies on domain characterization using photocurrent and scanning probe microscopy. I will then show that these polarization domains and their switching behavior can be probed by optical spectroscopy, revealing the existence of a variety of switching pathways. Due to their strong excitonic effects and sliding ferroelectricity, rhombohedral TMDs can be built into nonvolatile optical memories with high performances.

Speaker: Ziliang Ye, Associate Professor and Principal Investigator, Stewart Blusson Quantum Matter Institute