Collective modes in pumped unconventional superconductors with competing ground states 11. Januar 2022 | 14:15 Uhr - 15:45 Uhr

The recent technological development of THz spectroscopy makes it possible to probe properties of
quantum matter, which cannot be observed in equilibrium. This is of considerable interest in the field
of unconventional superconductivity, where controlled probing of the relaxation dynamics yields
access to understanding ground state proper-ties of the underlying system.
Motivated by the recent development of terahertz pump-probe experiments, I will discuss in my talk
the short-time dynamics in superconductors with multiple attractive pairing channels and competing
nematic instability. Studying a single-band and multiband superconductors, we analyze the signatures
of collective excitations of the pairing symmetries (known as Bardasis-Schrieffer modes) as well as the
order parameter amplitude (Higgs mode) in the short-time dynamics of the spectral gap and
quasiparticle distribution after an excitation by a pump pulse. We show that the polarization and
intensity of the pulse can be used to control the symmetry of the non-equilibrium state as well as
frequencies and relative intensities of the contributions of different collective modes.
Finanlly I address the question of whether pump-probe technique can be used to reveal an interplay
between various collective modes visible in the superconducting state and to distinguish the
Pomeranchuk nematic collective mode from the BS mode due to the subdominant Cooper-pairing
channel.

Referent*in

Prof. Dr. Ilya Eremin, Ruhr-Universität Bochum

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