Magnon bands in twisted bilayer honeycomb quantum magnets  

作　　者：Xingchuan Zhu Huaiming Guo Shiping Feng 朱兴川;郭怀明;冯世平(Department of Physics,Beijing Normal University,Beijing 100875,China;Key Laboratory of Micro-Nano Measurement-Manipulation and Physics(Ministry of Education),Department of Physics,Beihang University,Beijing 100191,China)

机构地区：[1]Department of Physics,Beijing Normal University,Beijing 100875,China [2]Key Laboratory of Micro-Nano Measurement-Manipulation and Physics(Ministry of Education),Department of Physics,Beihang University,Beijing 100191,China

出　　处：《Chinese Physics B》2021年第7期11-17,共7页中国物理B（英文版）

基　　金：the National Natural Science Foundation of China(Grant Nos.11774019,11974051,and 11734002);the Fundamental Research Funds for the Central Universities and the HPC Resources at Beihang University;the National Key Research and Development Program of China(Grant No.2016YFA0300304)。

摘　　要：We study the magnon bands of twisted bilayer honeycomb quantum magnets using linear spin wave theory.Although the interlayer coupling can be ferromagnetic or antiferromagnetic,we keep the intralayer one ferromagnetic to avoid possible frustration.For the interlayer ferromagnetic case,we find the magnon bands have similar features with the corresponding electronic energy spectrums.Although the linear dispersions near the Dirac points are preserved in the magnon bands of twisted bilayer magnets,their slopes are reduced with the decrease of the twist angles.On the other hand,the interlayer antiferromagnetic couplings generate quite different magnon spectra.The two single-layered magnon spectra are usually decoupled due to the opposite orientations of the spins in the two layers.We also develop a low-energy continuous theory for very small twist angles,which has been verified to fit well with the exact tight-binding calculations.Our results may be experimentally observed due to the rapid progress in two-dimensional magnetic materials.

关 键 词：magnon bands twisted bilayer quantum magnets linear spin wave theory 

分 类 号：O469[理学—凝聚态物理]