High-order nonlinear terahertz probing of the two-band superconductor MgB$_2$: Third- and fifth-order harmonic generation

C. Reinhoffer; P. Pilch; A. Reinold; P. Derendorf; S. Kovalev; J. -C. Deinert; I. Ilyakov; A. Ponomaryov; Min Chen; Tie-Quan Xu; Yue Wang; Zi-Zhao Gan; De-Sheng Wu; Jian-Lin Luo; S. Germanskiy; E. A. Mashkovich; P. H. M. van Loosdrecht; I. M. Eremin; Zhe Wang

doi:10.1103/physrevb.106.214514

arXiv · 2207.12361

High-order nonlinear terahertz probing of the two-band superconductor MgB$_2$: Third- and fifth-order harmonic generation

C. Reinhoffer·P. Pilch·A. Reinold·P. Derendorf·S. Kovalev·J. -C. Deinert·I. Ilyakov·A. Ponomaryov·Min Chen·Tie-Quan Xu·Yue Wang·Zi-Zhao Gan·De-Sheng Wu·Jian-Lin Luo·S. Germanskiy·E. A. Mashkovich·P. H. M. van Loosdrecht·I. M. Eremin·Zhe Wang

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Abstract

We report on high-order harmonic generation in the two-band superconductor MgB$_2$ driven by intense terahertz electromagnetic pulses. Third- and fifth-order harmonics are resolved in time domain and investigated as a function of temperature and in applied magnetic fields crossing the superconducting phase boundary. The high-order harmonics in the superconducting phase reflects nonequilibrium dynamics of the superconducting order parameter in MgB$_2$, which is probed via nonlinear coupling to the terahertz field. The observed temperature and field dependence of the nonlinear response allows to establish the superconducting phase diagram.

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C. Reinhoffer, P. Pilch, A. Reinold, P. Derendorf, S. Kovalev, J. -C. Deinert, I. Ilyakov, A. Ponomaryov, Min Chen, Tie-Quan Xu, Yue Wang, Zi-Zhao Gan, De-Sheng Wu, Jian-Lin Luo, S. Germanskiy, E. A. Mashkovich, P. H. M. van Loosdrecht, I. M. Eremin, Zhe Wang. 2022-07-25. High-order nonlinear terahertz probing of the two-band superconductor MgB$_2$: Third- and fifth-order harmonic generation. https://doi.org/10.1103/physrevb.106.214514

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