【直播】【施汝为系列讲座】加州理工学院周昊欣博士：菱方三层石墨烯中的铁磁和超导性

此次讲座由合肥微尺度物质科学国家研究中心、国际功能材料量子设计中心、中科院强耦合量子材料物理重点实验室、中国科大物理系、科研部联合主办，由低温物理学报承办，于2021年9月16日10:00开始。授权蔻享学术进行网络直播。

报告摘要

I will be presenting our observation of ferromagnetism and superconductivity in rhombohedral trilayer graphene. Rhombohedral trilayer graphene is a two-dimensional electron system where three layers of graphene are stacked to form a rhombohedral lattice. The band structure of rhombohedral trilayer graphene features van Hove singularities in the low energy regime, where the density of states diverges. The van Hove singularities can be enhanced by applying an electrical displacement field perpendicular to the sample, inducing Fermi surface instability. By combining cryogenic electrical transport measurement and quantum capacitance measurement, we found the Fermi surface instability drives spontaneous ferromagnetic polarization of the electron system into one or more spin- and valley flavors. The interplay of magnetic phase transitions and the change of the Fermi surface topology lead to a complex phase diagram in the density – displacement field space. More interestingly, superconductivity is observed near some phase boundaries, featuring zero resistance below 100mK that can be eliminated by sufficiently large electrical current or magnetic field. While the major features of the magnetic phase diagram can be captured by a simple Stoner model, the origin of superconductivity remains unclear. Our observation of the ferromagnetism and superconductivity in an itinerant electronic system may enable a new class of field-effect controlled mesoscopic electronic devices combining correlated electron phenomena.

报告人介绍

中国科大施汝为系列讲座链接：

https://www.koushare.com/live/srw

完