Boron Triangular Kagome Lattice with Half-Metallic Ferromagnetism

Sunghyun Kim,K J Chang,In-Ho Lee,W H Han

doi:10.1038/s41598-017-07518-9

Abstract

Based on the first-principles evolutionary materials design, we report a stable boron Kagome lattice composed of triangles in triangles on a two-dimensional sheet. The Kagome lattice can be synthesized on a silver substrate, with selecting Mg atoms as guest atoms. While the isolated Kagome lattice is slightly twisted without strain, it turns into an ideal triangular Kagome lattice under tensile strain. In the triangular Kagome lattice, we find the exotic electronic properties, such as topologically non-trivial flat band near the Fermi energy and half-metallic ferromagnetism, and predict the quantum anomalous Hall effect in the presence of spin-orbit coupling.

Highlights

Based on the first-principles evolutionary materials design, we report a stable boron Kagome lattice composed of triangles in triangles on a two-dimensional sheet
The experimental realization of the Kagome lattice is confined to the Kagome layers of pyrochlore oxides[19], the Cu ions sitting on a Kagome lattice in Herbertsmithite[12], the self-assembled metal-organic molecules on a substrate[20], and the cold atoms of an optical Kagome lattice[21]
On the Ag substrate, we find a Mg3B9 structure consisting of the B3 Kagome lattice and the Mg atoms located underneath the hexagonal holes (Fig. 2e), similar to MgB622

Summary

Introduction

Based on the first-principles evolutionary materials design, we report a stable boron Kagome lattice composed of triangles in triangles on a two-dimensional sheet. In the triangular Kagome lattice, we find the exotic electronic properties, such as topologically non-trivial flat band near the Fermi energy and half-metallic ferromagnetism, and predict the quantum anomalous Hall effect in the presence of spin-orbit coupling. Given the structural diversity of metal-B systems, a proper choice of substrate and metal elements as guest atoms can open the way to realizing stable 2D boron Kagome sheets that have not been discovered yet. The boron sheet separated from the substrate forms a twisted Kagome lattice and turns into an ideal triangular Kagome lattice under tensile strain, accompanied with a metal-to-half-metal transition. The ferromagnetism of the triangular Kagome lattice is characterized by a nearly flat band at the Fermi level, which is topologically non-trivial and induces the quantum anomalous Hall effect in the presence of spin-orbit coupling

Methods

Results

Conclusion