Possible Eliashberg-type superconductivity enhancement effects in a two-band superconductor MgB2 driven by narrow-band THz pulses

Sergei Sobolev; Amon Lanz; Tao Dong; Amrit Pokharel; Viktor Kabanov; Tie-Quan Xu; Yue Wang; Zi-Zhao Gan; L. Y. Shi; Nan-Lin Wang; Alexej Pashkin; Ece Uykur; Stephan Winnerl; Manfred Helm; Jure Demsar

arXiv · 2308.00775

Possible Eliashberg-type superconductivity enhancement effects in a two-band superconductor MgB2 driven by narrow-band THz pulses

Sergei Sobolev·Amon Lanz·Tao Dong·Amrit Pokharel·Viktor Kabanov·Tie-Quan Xu·Yue Wang·Zi-Zhao Gan·L. Y. Shi·Nan-Lin Wang·Alexej Pashkin·Ece Uykur·Stephan Winnerl·Manfred Helm·Jure Demsar

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Abstract

We study THz-driven condensate dynamics in epitaxial thin films of MgB$_{2}$, a prototype two-band superconductor (SC) with weak interband coupling. The temperature and excitation density dependent dynamics follow the behavior predicted by the phenomenological bottleneck model for the single-gap SC, implying adiabatic coupling between the two condensates on the ps timescale. The amplitude of the THz-driven suppression of condensate density reveals an unexpected decrease in pair-breaking efficiency with increasing temperature - unlike in the case of optical excitation. The reduced pair-breaking efficiency of narrow-band THz pulses, displaying minimum near $\approx0.7$ T$_{c}$, is attributed to THz-driven, long-lived, non-thermal quasiparticle distribution, resulting in Eliashberg-type enhancement of superconductivity, competing with pair-breaking.

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Sergei Sobolev, Amon Lanz, Tao Dong, Amrit Pokharel, Viktor Kabanov, Tie-Quan Xu, Yue Wang, Zi-Zhao Gan, L. Y. Shi, Nan-Lin Wang, Alexej Pashkin, Ece Uykur, Stephan Winnerl, Manfred Helm, Jure Demsar. 2023-08-01. Possible Eliashberg-type superconductivity enhancement effects in a two-band superconductor MgB2 driven by narrow-band THz pulses. https://arxiv.org/abs/2308.00775

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