Observation of terahertz-induced dynamical spin canting in orthoferrite magnon by magnetorefractive probing
Observation of terahertz-induced dynamical spin canting in orthoferrite magnon by magnetorefractive probing
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DOI：
10.1038/s42005-023-01167-3
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发表时间：
2023-03
影响因子：
5.5
通讯作者：
T. Kurihara;M. Bamba;Hiroshi Watanabe;M. Nakajima;T. Suemoto
中科院分区：
文献类型：
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作者：
T. Kurihara;M. Bamba;Hiroshi Watanabe;M. Nakajima;T. Suemoto
强烈的太赫兹脉冲提供了独特的途径来共振驱动相关自旋系统达到非线性状态。然而，这种非线性自旋动力学的检测通常会受到信号幅度小的影响，很容易受到线性背景分量的阻碍。为了有效地提取非线性信号，这里我们证明可以利用磁光效应。我们通过强太赫兹脉冲磁场激发正铁氧体YFeO3中的自旋进动，并通过近红外瞬态透射率变化来探测其动力学。观察到的波形包含准铁磁模式磁振子振荡及其具有相对强振幅的二次谐波。该结果可以通过磁折射哈密顿量导出的介电函数来解释。我们揭示了强二次谐波信号在微观上源自非线性状态下准铁磁模式磁振子的动力学，其中自旋倾斜角周期性振荡。
Intense terahertz pulses offer unique pathway to resonantly drive the correlated spin systems up to the nonlinear regime. However, detection of such nonlinear spin dynamics often suffers from the small signal amplitude that can be easily hindered by the linear background components. In order to efficiently extract the nonlinear signals, here we demonstrate that magnetooptical effect can be utilized. We excite spin precession in orthoferrite YFeO3by the magnetic field of intense terahertz pulse and probe its dynamics by transient transmissivity change in the near infrared. The observed waveforms contain quasi-ferromagnetic-mode magnon oscillation and its second harmonics with a comparably strong amplitude. The result can be explained by dielectric function derived from magnetorefractive Hamiltonian. We reveal that the strong second harmonic signal microscopically originates from the dynamics of the quasi-ferromagnetic mode magnon at nonlinear regime, wherein spin canting angle periodically oscillates.