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arXiv · 2106.15478

High-order Harmonic Generation and its Unconventional Scaling Law in the Mott-insulating $\rm{Ca_2RuO_4}$

K. Uchida·G. Mattoni·S. Yonezawa·F. Nakamura·Y. Maeno·K. Tanaka
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Abstract

Competition and cooperation among orders is at the heart of many-body physics in strongly correlated materials and leads to their rich physical properties. It is crucial to investigate what impact many-body physics has on extreme nonlinear optical phenomena, with the possibility of controlling material properties by light. However, the effect of competing orders and electron-electron correlations on highly nonlinear optical phenomena has not yet been experimentally clarified. Here, we investigated high-order harmonic generation from the Mott-insulating phase of Ca2RuO4. Changing the gap energy in Ca2RuO4 as a function of temperature, we observed a strong enhancement of high order harmonic generation at 50 K, increasing up to several hundred times compared to room temperature. We discovered that this enhancement can be well-reproduced by an empirical scaling law that depends only on the material gap energy and photon emission energy. Such scaling law cannot be explained by a simple two-band model under the single electron approximation. Our results suggest that the highly nonlinear optical response of strongly correlated materials is deeply coupled to their electron-electron correlations and resultant many-body electronic structure.

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K. Uchida, G. Mattoni, S. Yonezawa, F. Nakamura, Y. Maeno, K. Tanaka. 2021-06-29. High-order Harmonic Generation and its Unconventional Scaling Law in the Mott-insulating $\rm{Ca_2RuO_4}$. https://doi.org/10.1103/physrevlett.128.127401

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