Low-Frequency Divergence of Circular Photomagnetic Effect in Topological Semimetals

TL;DR

This paper reveals that topological semimetals exhibit an unusual low-frequency enhancement in their circular photomagnetic response due to their topological properties, making them promising for optoelectronic applications.

Contribution

It uncovers an unconventional $oldsymbol{ extomega^{-1}}$ frequency scaling in the circular photomagnetic effect of topological semimetals, linking response to their topological invariants.

Findings

Enhanced low-frequency response due to $oldsymbol{ extomega^{-1}}$ scaling.

Response directly related to Chern numbers of emergent fermions.

Potential for applications in optoelectronics and spintronics.

Abstract

Novel fermions with relativistic linear dispersion can emerge as low-energy excitations in topological semimetal materials. Here, we show that the orbital moment contribution in the circular photomagnetic effect for these topological semimetals exhibit an unconventional $\omega^{-1}$ frequency scaling, leading to significantly enhanced response in the low frequency window, which can be orders of magnitude larger than previous observations on conventional materials. Furthermore, the response tensor is directly connected to the Chern numbers of the emergent fermions, manifesting their topological character. Our work reveals a new signature of topological semimetals and suggests them as promising platforms for optoelectronics and spintronics applications.