Theory seminars for the Autumn 2016
Chiral plasmons without magnetic field
In electronic systems, chirality is an interesting and useful property that expresses the system's ability to discriminate between forward and backward propagation along certain directions. Edge states in the quantum Hall effect provide a classic example.
Recently, materials exhibiting chirality in the absence of an applied magnetic field have come into the spotlight. Here, the Berry curvature inherent in the material's band structure crucially alters the motion of free carriers, leading to a variety of interesting phenomena such as the anomalous, spin, and valley Hall effects. In this work we show that the interplay between electron-electron interactions and Bloch band Berry curvature leads to a new type of electronic collective excitation -- the chiral Berry plasmon -- with a variety of properties of both fundamental and potential technological interest.
In this talk I will review the basics of Bloch band Berry curvature and related anomalous transport effects, and then demonstrate how these new chiral plasmon modes emerge at the edges of appropriate 2D systems. Experimental signatures and candidate materials including anomalous Hall and quantum anomalous Hall systems, as well as optically pumped gapped Dirac systems (such as hexagonal boron nitride and transition metal dichalcogenides) will be discussed.