Abstract: Understanding and manipulating macroscopic quantum phenomena such as
superconductivity and magnetism are crucial for future quantum science and
technology. Two-dimensional (2D) materials and their van der Waals (vdW)
heterostructures offer a promising platform to achieve this goal due to their
exceptionally broad tunability. In this talk, I will highlight the potential of
such a platform through two outstanding examples: 2D magnetism and 2D
superconductivity. In the first part, I will talk about a series of emergent
phenomena enabled by the vdW nature of 2D magnets, including (1) giant
tunneling magnetoresistance enhanced by spin-filtering effects; (2) control of
interlayer magnetism by tuning layer stacking; (3) novel moiré magnetism by
twisting two layers of 2D magnets. In the second part, I will introduce a new
probe to detect superconducting fluctuations down to millikelvin temperatures
based on thermoelectric measurements of a monolayer nanoflake. I will discuss
surprisingly unusual vortex Nernst signals, which reveal an unconventional
superconducting quantum criticality in an electrically tunable 2D
superconductor. Finally, I will conclude by highlighting unique opportunities
for discovering and engineering new quantum materials and electronic phases in
two dimensions.