Advancing crystal quality and quantum phenomena in thin film WTe₂ (part 1)

The ability to harness impurity and disorder in quantum materials is a key to ensure the observation and reproducibility of the many emergent phenomena. Transition metal dichalcogenides (TMDs) is one example where many quantum states such as fractional quantum anomalous Hall effect and unconventional superconductivity are actively being explored. However, high intrinsic point defects often result in low mobility, obscure the intrinsic physics and hinder device functionality. We adapt a horizontal flux transport method to grow single-crystal TMDs with significantly improved quality. Using WTe₂ as an example, we demonstrate an order-of-magnitude improvement in sample quality as characterized by residual resistivity ratio. The enhanced crystal quality led to much higher mobility and more prominent quantum phenomena in bulk and thin film form. Our work highlights the critical role of crystal quality in TMDs for realizing exotic physics and shed light to the future optimization and mobility engineering of quantum materials.