High-order nonlinear terahertz probing of the two-band superconductor MgB2 : Third- and fifth-order harmonic generation
/ Authors
C. Reinhoffer, P. Pilch, A. Reinold, P. Derendorf, S. Kovalev, J. Deinert, I. Ilyakov, A. Ponomaryov, Min Chen, T. Xu
and 9 more authors
Yue Wang, Z. Gan, Desheng Wu, Jianlin Luo, S. Germanskiy, E. Mashkovich, P. V. van Loosdrecht, I. Eremin, Zhe Wang
/ 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.
Journal: Physical Review B