Probing ultrafast spin-relaxation and precession dynamics in a cuprate Mott insulator with 7-fs optical pulses
| Autor: | Miyamoto, T., Matsui, Y., Terashige, T., Morimoto, T., Sono, N., Yada, H., Ishihara, S., Watanabe, Y., Adachi, S., Ito, T., Oka, K., Sawa, A., Okamoto, H. |
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| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | Nat. Commun. 9 (2018) 3948 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1038/s41467-018-06312-z |
| Popis: | A charge excitation in a two-dimensional Mott insulator is strongly coupled with the surrounding spins, which is observed as magnetic-polaron formations of doped carriers and a magnon sideband in the Mott-gap transition spectrum. However, the dynamics related to the spin sector are difficult to measure. Here, we show that pump-probe reflection spectroscopy with 7-fs laser pulses can detect the optically induced spin dynamics in Nd$_2$CuO$_4$, a cuprate Mott insulator. The bleaching signal at the Mott-gap transition is enhanced at $\sim$18 fs, which corresponds to the spin-relaxation time in magnetic-polaron formations and is characterized by the exchange interaction. More importantly, ultrafast coherent oscillations appear in the time evolutions of the reflectivity changes, and their frequencies (1400-2700 cm$^{-1}$) are equal to the probe energy measured from the Mott-gap transition peak. These oscillations originate from interferences between charge excitations with two magnons and provide direct evidence for charge-spin coupling. Comment: 20 pages including 4 figures (Supplementary materials: 11 pages including 4 figures) |
| Databáze: | arXiv |
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