Formisano F, Dubrovin R M, Pisarev R V, Kalashnikova A M, Kimel A V
Institute for Molecules and Materials, Radboud University, 6571AJ Nijmegen, The Netherlands.
Ioffe Institute, 194021 St. Petersburg, Russia.
J Phys Condens Matter. 2022 Mar 30;34(22). doi: 10.1088/1361-648X/ac5c20.
Excitation, detection, and control of coherent THz magnetic excitation in antiferromagnets are challenging problems that can be addressed using ever shorter laser pulses. We study experimentally excitation of magnetic dynamics at THz frequencies in an antiferromagnetic insulator CoFby sub-10 fs laser pulses. Time-resolved pump-probe polarimetric measurements at different temperatures and probe polarizations reveal laser-induced transient circular birefringence oscillating at the frequency of 7.45 THz and present below the Néel temperature. The THz oscillations of circular birefringence are ascribed to oscillations of the magnetic moments of Coions induced by the laser-driven coherentphonon mode via the THz analogue of the transverse piezomagnetic effect. It is also shown that the same pulse launches coherent oscillations of the magnetic linear birefringence at the frequency of 3.4 THz corresponding to the two-magnon mode. Analysis of the probe polarization dependence of the transient magnetic linear birefringence at the frequency of the two-magnon mode enables identifying its symmetry.
在反铁磁体中，相干太赫兹磁激发的激发、检测和控制是具有挑战性的问题，可通过使用越来越短的激光脉冲来解决。我们通过亚10飞秒激光脉冲对反铁磁绝缘体CoF中太赫兹频率下的磁动力学激发进行了实验研究。在不同温度和探测偏振下的时间分辨泵浦-探测偏振测量揭示了在奈尔温度以下以7.45太赫兹频率振荡的激光诱导瞬态圆双折射。圆双折射的太赫兹振荡归因于激光驱动的相干声子模式通过横向压磁效应的太赫兹类似物诱导的钴离子磁矩振荡。研究还表明，同一脉冲在3.4太赫兹频率下引发了对应于双磁子模式的磁线性双折射的相干振荡。对双磁子模式频率下瞬态磁线性双折射的探测偏振依赖性分析能够确定其对称性。
