Photoexcited d-electron dynamics in transition metal oxide MnO studied by optical pump-THz probe measurements
Photoexcited d-electron dynamics in transition metal oxide MnO studied by optical pump-THz probe measurements
复制标题
通过光泵-太赫兹探针测量研究过渡金属氧化物 MnO 中的光激发 d 电子动力学
DOI：
10.1002/pssc.201510086
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
and T. Suemoto
中科院分区：
文献类型：
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作者：
J. Nishitani;T. Kurihara;A. Asahara;T. Nagashima;M. Lippmaa;and T. Suemoto
光泵浦太赫兹探测（opticalpump-THz probe，OPTP）技术可以通过观察太赫兹光激发后透射率的瞬态变化来研究材料中光电导的动态响应。在这项研究中，d电子在MnO中的各种光激发态的THz响应通过泵浦能量可调谐的OPTP测量来研究，以阐明过渡金属氧化物中的光激发d电子动力学。在室温下，光激发dd-电子诱导的ad-d跃迁到最低激发dd-状态显示出最长的弛豫时间。在反铁磁转变温度120 K以下，弛豫时间急剧下降.这种减少伴随着自陷激子（STE）状态的磁激发辅助光致发光的出现。这表明光激发的dd电子在转变温度以下弛豫到STE状态。这些发现为光激发电子动力学提供了新的线索，与先前研究中通过载流子散射松弛到陷阱态的上激发态中产生的光激发载流子的行为形成对比。（© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA，魏因海姆）
Optical pump‐THz probe (OPTP) measurements allow us to investigate the dynamic response of photoconductivity in materials by observing the transient change of THz transmittance after optical excitation. In this study, the THz response ofd‐electrons in various photoexcited states in MnO was investigated by pump‐energy‐tunable OPTP measurements to elucidate the photoexcitedd‐electron dynamics in a transition metal oxide. At room temperature, photoexcitedd‐electrons induced by ad‐dtransition to the lowest excitedd‐state showed the longest relaxation time. The relaxation time decreased drastically below the antiferromagnetic transition temperature of 120 K. This decrease was accompanied by the emergence of magnetic‐excitation‐assisted photoluminescence from a self‐trapped exciton (STE) state. This suggests that photoexcitedd‐electrons relax to the STE state below the transition temperature. These findings shed new light on the photoexcitedd‐electron dynamics, contrasting with the behavior of photoexcited carriers generated in the upper excitedd‐states that have been shown in a previous study to relax into trap states through carrier scattering. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)