Speaker: Dr. Jiang-Xiazi Lin 

Host: Prof. Zhigang Jiang

Title: Hysterically driven anisotropic phase in rhombohedral graphene

Abstract: In the flat-band limit of 2D materials, Coulomb interactions dominate the electronic behavior and give rise to a plethora of symmetry-broken electronic phases. One example is the spontaneous polarization of valleys—a pair of low-energy bands with opposite momenta related by time reversal. Such a valley ferromagnetic state can by detected through magnetic hysteresis in transport measurements. Another example is the spontaneous breaking of rotational symmetry, leading to anisotropic electronic order. This phenomenon remains less explored due to geometric limitations of devices.

Here we report an experimental observation of an intriguing interplay between these two types of spontaneous symmetry breaking in a rhombohedral hexalayer graphene device, using angle-resolved transport studies. Our findings point to the emergence of rotational-symmetry-broken valley domains or stripe order. More interestingly, this anisotropic phase can be switched on and off via electrostatic doping—a phenomenon that cannot be explained by electronic order alone. In this talk, I will present these experimental observations and discuss potential explanations.

Bio: Jiang-Xiazi Lin is an Assistant Professor of Physics at Emory University. She joined Emory in 2024 after completing her postdoctoral research at Brown University, where she focused on magic-angle twisted graphene. Prior to that, she earned her Ph.D. from Hong Kong University of Science and Technology. At Emory, she leads an experimental research group and continues to build on her expertise in fabricating 2D van der Waals devices and performing transport measurements in dilution refrigerator. Her current research interests center on flat-band electronic phases in 2D quantum materials.