Flat-band based high-temperature ferromagnetic semiconducting state in the graphitic C4N3 monolayer  

作　　者：Chaoyu He Yujie Liao Tao Ouyang Huimin Zhang Hongjun Xiang Jianxin Zhong 

机构地区：[1]Laboratory for Quantum Engineering and Micro-Nano Energy Technology and School of Physics and Optoelectronics,Xiangtan University,Xiangtan 411105,China [2]Key Laboratory of Computational Physical Sciences(Ministry of Education),Institute of Computational Physical Sciences,Department of Physics,Fudan University,Shanghai 200433,China

出　　处：《Fundamental Research》2025年第1期138-144,共7页自然科学基础研究(英文版)

基　　金：supported by the National Natural Science Foundation of China(52372260,11974300,11974299 and 12204397);the Science Fund for Distinguished Young Scholars of Hunan Province of China(2021JJ10036);the Youth Science and Technology Talent Project of Hunan Province(2022RC1197);Work at Fudan is supported by NSFC(11825403,11991061,and 12188101);Guangdong Major Project of Basic and Applied Basic Research(Future functional materials under extreme conditions-2021B0301030005);H.-M.Z was supported by the Jiangsu Funding Program for Excellent Postdoctoral Talent.

摘　　要：Half-filled isolated flat-band paves a new way to realize high-temperature ferromagnetic semiconductor for spintronics applications,but it is extremely rare in lattice models and lacking in realistic materials.Herein,the 2×2 super-cell of the honeycomb lattice with a single-hole defect is proposed as a new lattice model(HL-D-1/8)to realize nontrivial isolated flat-bands.We further demonstrate that C_(4)N_(3)monolayer of the experimentally realized graphitic carbon nitride(Adv.Mater.,22,1004,2010;Nat.Commun.,9,3366,2018)is a perfect system holding such a lattice to host flat-bands.A new corrugated Pca21 configuration is proposed as the ground state for the free-standing C_(4)N_(3)monolayer,which is dynamically stable and energetically more favorable than the widely-used flat one without dynamical stability.The Pca21 configuration is found to be an intrinsic ferromagnetic half-semiconductor(T_(c)≈241 K)with one semiconducting spin-channel(1.75 eV)and one insulating spin-channel(3.64 eV),which is quite rare in two-dimensional systems.Its ferromagnetic semiconducting property originates from the isolated pz-state flat-band as the corrugation shifts the flat-band upward to the Fermi level.Interestingly,such a corrugated Pca21 C_(4)N_(3)monolayer is found to be both piezoelectric and ferroelectric,which makes it an unusual metal-free two-dimensional multiferroic.

关 键 词：Graphitic C_(4)N_(3) Isolated flat-band Ferromagnetic semiconductor Two-dimensional multiferroic First-principles calculation Tight-binding model 

分 类 号：O73[理学—晶体学]