Journal
PHYSICAL REVIEW B
Volume 102, Issue 12, Pages -Publisher
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.102.125115
Keywords
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Funding
- US Department of Energy-Basic Energy Sciences [DE-FG02-04ER46148]
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Circular dichroism (CD) is generally observed in the optically active chiral molecules that originate from macroscopic electric and magnetic dipoles, which is usually quite small. In solid states, the so-called valley CD may arise microscopically from interband transitions between two chiral electronic valley bands of nonzero Berry curvatures at a given k point. However, generally, two sets of K and K' valleys coexist in the Brillouin zone with opposite chiral selectivities, so that the net CD is zero for the whole material. Here, we demonstrate a giant CD originating from photoexcitation between two chiral Chern flat bands of opposite Chern numbers, namely, the enantiomorphic flat Chern bands. The dissymmetry factor g of such flat CD can reach the theoretical maximum value of 2 with the optimal spin-orbit coupling strength. Based on first-principles calculations, we identify that the Li intercalated bilayer pi-conjugated nickel-bis(dithiolene) hosts a set of yin-yang kagome bands with an estimated large g = 0.74 under magnetic field. Furthermore, based on the flat-CD mechanism, we propose two flatband devices of topological photodetectors and circularly polarized lasers.
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