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Published on: March 27, 2018
A new type of stable borophene with flat-band-induced magnetism
Zhijian Li1,2, Yang Xue3, Qingzhao Yao1,2
1State Key Laboratory of Surface Physics and Key Laboratory of Computational Physical Sciences (MOE) and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China.
Abstract:
Based on first-principles calculations, we propose a new type of thermally and dynamically stable magnetic borophene (B11) with a tetragonal lattice. The magnetism is found coming from spin polarization of one bonding flat band located at the Fermi level. Despite of the 'anti-molecular' behavior in the monolayer, the interactions between thepzorbitals of the B atoms in the double-octahedron structural unit lead to the formation of the flat bands with localization behaviors. One tight binding model is built to comprehend the magnetic mechanism, which can guide us to tune other nonmagnetic borophene becoming magnetic. Biaxial tensile strain (>2.1%) is found triggering a phase transition from a semimetal to a semiconductor in the B11monolayer. The mechanism is analyzed based on the orbital-resolved crystal field effect. Our work provides a new route for designing and achieving two-dimensional magnetic materials with light elements.
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