摘要
Antiferromagnets exhibit distinctive characteristics such as ultrafast dynamics and robustness against perturbative fields,thereby attracting considerable interest in fundamental physics and technological applications.Recently,it was revealed that the Néel vector can be switched by a current-induced staggered(Néel)spin-orbit torque in antiferromagnets with the parity-time symmetry,and furthermore,a nonsymmorphic symmetry enables the control of Dirac fermions.However,the real-time dynamics of the magnetic and electronic structures remain largely unexplored.Here,we propose a theory of the ultrafast dynamics in antiferromagnetic Dirac semimetals and show that the Néel vector is rotated in the picosecond timescale by the terahertz-pulse-induced Néel spin-orbit torque and other torques originating from magnetic anisotropies.This reorientation accompanies the modulation of the mass of Dirac fermions and can be observed in real time by the magneto-optical effects.Our results provide a theoretical basis for emerging ultrafast antiferromagnetic spintronics combined with the topological aspects of materials.
基金
One of the authors,Sumio Ishihara,passed away on 7 November 2020 during the preparation of the manuscript.We thank H.Matsueda and Y.Masaki for their valuable comments and critical reading of the manuscript.This work was supported by JSPS KAKENHI Grant Nos.JP19K23419,JP20K14394,JP17H02916,JP18H05208,and JP20H00121
The numerical calculations were performed using the facilities of the Supercomputer Center,the Institute for Solid State Physics,the University of Tokyo。
