Condensed Matter Physics Seminar - Pavol Neilinger (25.10.2019)
Friday 25.10.2019 at 13:00, Lecture room F2/272
By: Richard Hlubina
Observation of quantum corrections to conductivity up to optical frequencies
Disordered conductors are a permanent subject of research, largely motivated by the appeal of dealing with the most fundamental issues of condensed matter physics. The frequency-dependent conductivity of metals is, in the simplest case, described by the Drude formula. For strongly disordered conductors, deviations from this formula due to quantum eﬀects are well-known. However, these corrections are traditionally considered an esoteric low-energy phenomenon and have so far been experimentally proven only for .80 meV.
This talk will be devoted to quantum corrections to the conductivity of disordered MoC thin ﬁlms . By a combination of transport and optical studies, I will show that the quantum corrections are very robust in these ﬁlms, being present up to ultraviolet frequencies (at least∼4 eV). The knowledge of the real part of the optical conductivity - obtained from transport and optical transmission measurements, and the imaginary part of conductivity - obtained from optical ellipsometry, provides the means to identify the microscopic parameters of the conduction electron ﬂuid and to determine the absolute magnitude of the quantum correction, which was not previously possible. This new methodology can be utilized to study other disordered conductors, such as TiN, NbN, SiN, and InO and can contribute to the understanding of their electric properties.
 P. Neilinger et al., arxiv.org/abs/1908.09907