Haoxin Zhou: Ferromagnetism and superconductivity in rhombohedral trilayer graphene
2:00 pm - 3:00 pm
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Graduate Student Researcher
UC Santa Barbara
My name is Haoxin Zhou, I am a graduate student working with Prof. Andrea Young in the Department of Physics at UCSB. My research has been focusing on studying electronic correlations in graphene Van der Waals heterostructures by cryogenic electrical measurement. Before I joined UCSB, I earned a bachelor’s degree from the University of Science and Technology of China in 2015.
In this presentation, I will report our observation of ferromagnetism and superconductivity in rhombohedral (ABC-stacked) trilayer graphene. Under an applied electrical displacement field, rhombohedral trilayer graphene is a semiconductor with an unusually flat band minimum. By fabricating dual-graphite gated Van der Waals heterostructures, disorder effect is effectively suppressed, and ballistic conduction is observed. This allows us to combine capacitance and transport measurements to study the spin- and valley- polarization as well as the details of the Fermi surfaces. We show that the high density of states near the band bottom leads to magnetic phase transitions in which one or more of the spin- and valley- symmetries are broken. In states with annular Fermi surfaces, multiple superconducting states emerge at low temperature. Our observation of the ferromagnetism and superconductivity in a ballistic electronic system enables a new class of field-effect controlled mesoscopic electronic devices combining correlated electron phenomena.