Tsutsui Kenji, Shinjo Kazuya, Tohyama Takami
Synchrotron Radiation Research Center, National Institutes for Quantum and Radiological Science and Technology, Hyogo 679-5148, Japan.
Department of Applied Physics, Tokyo University of Science, Tokyo 125-8585, Japan.
Phys Rev Lett. 2021 Mar 26;126(12):127404. doi: 10.1103/PhysRevLett.126.127404.
Motivated by the recent development of time-resolved resonant-inelastic x-ray scattering (TRRIXS) in photoexcited antiferromagnetic Mott insulators, we numerically investigate momentum-dependent transient spin dynamics in a half-filled Hubbard model on a square lattice. After turning off a pumping photon pulse, the intensity of a dynamical spin structure factor temporally oscillates with frequencies determined by the energy of two magnons in the antiferromagnetic Mott insulator. We find an antiphase behavior in the oscillations between two orthogonal momentum directions, parallel and perpendicular to the electric field of a pump pulse. The phase difference comes from the B_{1g} channel of the two-magnon excitation. Observing the antiphase oscillations will be a big challenge for TRRIXS experiments when their time resolution will be improved by more than an order of magnitude.
受光激发反铁磁莫特绝缘体中时间分辨共振非弹性X射线散射（TRRIXS）近期发展的推动，我们对正方晶格上半填充哈伯德模型中与动量相关的瞬态自旋动力学进行了数值研究。在关闭泵浦光子脉冲后，动态自旋结构因子的强度随时间振荡，其频率由反铁磁莫特绝缘体中两个磁振子的能量决定。我们发现在与泵浦脉冲电场平行和垂直的两个正交动量方向之间的振荡中存在反相行为。相位差来自于两个磁振子激发的B₁g通道。当TRRIXS实验的时间分辨率提高一个数量级以上时，观察到这种反相振荡将是一个巨大的挑战。
