Professor Liang Fu
MIT
Manifestations of the Berry Phase: From Fractional Charge to Wireless Rectification
Location: 1080 Physics Research Building
Faculty Host: Brian Skinner
Abstract: The Berry phase represents the phase shift a quantum state acquires when undergoing a cyclic change. In this talk, I will describe two fascinating phenomena that arise from electron's Berry phase in quantum materials. First, I will discuss the discovery of the nonlinear Hall effect, which is driven by the Berry phase in momentum space and can occur in polar crystals without the need for an external magnetic field. This effect generates a DC transverse current in response to an AC voltage, thereby enabling wireless rectification across an exceptionally broad frequency range, from RF to THz. Next, I will explore how the Berry phase associated with real-space "spin" textures leads to the formation of flat topological bands that mimic Landau levels, giving rise to fractional quantum Hall-like states in the absence of a magnetic field.
Bio: Liang Fu joined the MIT Physics Department as an Assistant Professor in January 2012. He obtained a Bachelor’s degree in Physics from the University of Science and Technology of China in 2004 and PhD in Physics from the University of Pennsylvania in 2009. Before coming to MIT, he was a Junior Fellow at Harvard University.
