Indexed by: Journal paper

First Author: Ching Hua Lee

Correspondence Author: Jiangbin Gong,Xiao Zhang

Co-author: Gang Xu,Tommy Tai,Han Hoe Yap

Journal: Physical Review B

Included Journals: SCI

Discipline: Science

First-Level Discipline: Physics

Document Type: J

Volume: 102

Issue: 3

Page Number: 35138

ISSN No.: 2469-9950

Date of Publication: 2020-07-21

Impact Factor: 4.036

Abstract: Among topological materials, nodal loop semimetals are arguably the most topologically sophisticated, with their valence and conduction bands intersecting along arbitrarily intertwined nodes. But unlike the well-known topological band insulators with quantized edge conductivities, nodal loop materials possess topologically nontrivial Fermi surfaces, not bands. Hence an important question arises: Are there also directly measurable or even technologically useful physical properties characterizing nontrivial nodal loop topology? In this paper, we provide an affirmative answer by showing that nodal linkages protect the higher harmonic generation (HHG) of electromagnetic signals. Specifically, nodal linkages enforce nonmonotonicity in the intraband semiclassical response of nodal materials, which will be robust against perturbations preserving the nodal topology. These nonlinearities distort incident radiation and produce higher frequency peaks in the teraHertz (THz) regime, as we quantitatively demonstrate for a few known nodal materials. Since THz sources are not yet ubiquitous, our new mechanism for HHG will greatly aid applications like material characterization and nonionizing imaging of object interiors.

Links to published journals: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.102.035138