Isolated flat bands in an interlocking-circles lattice

TL;DR

This paper introduces a novel interlocking-circles lattice that produces isolated flat bands, realized in hydrogenated graphene, enabling potential applications in spintronics and ferromagnetism.

Contribution

It proposes a new lattice pattern capable of generating isolated flat bands and demonstrates its realization in hydrogenated graphene.

Findings

Two nontrivial isolated flat bands near the Fermi level in hydrogenated graphene.

Doping causes spin polarization and ferromagnetism in the flat-band system.

The interlocking-circles lattice design can be used to find other systems with isolated flat bands.

Abstract

Flat-band physics has attracted much attention in recently years because of its interesting properties and important applications. Some typical lattices have been proposed to generate flat bands, such as Kagome and Lieb lattices. The flat bands in these lattices contact with other bands rather than isolated. However, an ideal flat band should be isolated, because isolation is a prerequisite for a number of important applications. Here, we propose a new lattice that can produce isolated flat bands. The lattice is named as interlocking-circles lattice because its pattern seems like interlocking circles. Moreover, the new lattice is realized in graphene by hydrogenation. In the hydrogenated graphene, there are two nontrivial isolated flat bands appearing around the Fermi level. Upon hole or electron doping, the flat bands split into spin-polarized bands and then result in a ferromagnetic graphene. Our work not only proposes a new type of lattice but also opens a way to find systems with isolated flat bands.