A5027244532- Organic and Molecular Conductors Research
- Magnetism in coordination complexes
- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Iron-based superconductors research
- Rare-earth and actinide compounds
- Solid-state spectroscopy and crystallography
- Quantum and electron transport phenomena
- Magnetic and transport properties of perovskites and related materials
- Topological Materials and Phenomena
- Perovskite Materials and Applications
- Molecular Junctions and Nanostructures
- Advanced Chemical Physics Studies
- Inorganic Fluorides and Related Compounds
- Spectroscopy and Quantum Chemical Studies
- N-Heterocyclic Carbenes in Organic and Inorganic Chemistry
- Electron Spin Resonance Studies
- Crystallization and Solubility Studies
- Electronic and Structural Properties of Oxides
- Magnetic properties of thin films
- Lanthanide and Transition Metal Complexes
- X-ray Diffraction in Crystallography
- Multiferroics and related materials
- Inorganic Chemistry and Materials
- Terahertz technology and applications
University of Stuttgart
2016-2025
Moscow Institute of Physics and Technology
2013-2022
Center for Integrated Quantum Science and Technology
2020
Moscow Power Engineering Institute
2020
Moscow Aviation Institute
2020
Jet Propulsion Laboratory
2020
Space Information Laboratories (United States)
2020
North Carolina State University
2020
Aalto University
2020
The University of Western Australia
2020
We review studies of the electromagnetic response various classes correlated electron materials including transition metal oxides, organic and molecular conductors, intermetallic compounds with $d$- $f$-electrons as well magnetic semiconductors. Optical inquiry into correlations in all these diverse systems is enabled by experimental access to fundamental characteristics an ensemble electrons their self-energy kinetic energy. Steady-state spectroscopy carried out over a broad range...
1. Introduction Part I. Concepts and Properties: 2. The interaction of radiation with matter 3. General properties the optical constants 4. medium: correlation response functions 5. Metals 6. Semiconductors 7. Broken-symmetry states metals II. Methods: 8. Techniques: general considerations 9. Propagation scattering electromagnetic waves 10. Spectroscopic principles 11. Measurement configurations III. Experiments: 12. 13. 14. Appendix A. Fourier Laplace transformation B. Medium finite...
Coexisting density-wave and superconducting states along with the large anomalous Hall effect in absence of local magnetism remain intriguing enigmatic features AV$_3$Sb$_5$ kagome metals (A = K, Rb, Cs). Here, we demonstrate via optical spectroscopy density-functional calculations that low-energy dynamics KV$_3$Sb$_5$ is characterized by unconventional localized carriers, which are strongly renormalized across transition indicative electronic correlations. Strong phonon anomalies prominent...
Thorough Raman and infrared (IR) reflectivity investigations of nominally pure ${\mathrm{SrTiO}}_{3}$ ceramics in the 10--300 K range have revealed a clear presence polar phase whose manifestation steeply increases on cooling. The strengths Raman-forbidden IR modes are proportional to ${\ensuremath{\omega}}_{\mathrm{TO}1}^{\ensuremath{-}\ensuremath{\alpha}}(\ensuremath{\alpha}\ensuremath{\approx}1.6)$ where ${\ensuremath{\omega}}_{\mathrm{TO}1}$ is soft mode frequency. No pronounced...
We have measured the electrodynamic response in metallic state of three highly anisotropic conductors, $(\mathrm{TMTSF}{)}_{2}X,$ where $X={\mathrm{PF}}_{6}$, ${\mathrm{AsF}}_{6},$ or ${\mathrm{ClO}}_{4},$ and TMTSF is organic molecule tetramethyltetraselenofulvalene. In all cases we find dramatic deviations from a simple Drude response. The optical conductivity has two features: narrow mode at zero frequency, with small spectral weight, centered around 200...
Dielectric spectroscopy up to 370 GHz has been performed on supercooled glycerol for temperatures between 250 and 330 K. The high-frequency dielectric loss, ${\ensuremath{\varepsilon}}^{\ensuremath{'}\ensuremath{'}}$, investigated by coherent-source submillimeter-wave spectroscopy. Special attention is given the loss in crossover regime from structural relaxation far-infrared response. A minimum observed ${\ensuremath{\varepsilon}}^{\ensuremath{'}\ensuremath{'}}(\ensuremath{\nu})$ which...
The polarization dependence of the low field microwave photoconductivity and absorption a two-dimensional electron system has been investigated in quasi-optical setup which linear any circular can be produced in-situ. induced resistance oscillations zero regions are notedly immune to sense polarization. This observation is discrepant with number proposed theories. Deviations only occur near cyclotron resonance where an unprecedented large response observed.
Direct evidence of quantum coherence in a single-molecule magnet frozen solution is reported with times as long T{2}=630+/-30 ns. We can strongly increase the time by modifying matrix which magnets are embedded. The electron spins coupled to proton nuclear both molecule itself and, interestingly, also those solvent. clear observation Rabi oscillations indicates that we manipulate spin coherently, an essential prerequisite for performing computations.
We report on optical reflection measurements of thin Au films at and around the percolation threshold (film thickness 3 to 10 nm) in an extremely broad spectral range from 500 35000 cm-1 (0.3 - 20 *10-6 m). Combining spectroscopic ellipsometry Fourier-transform infrared spectroscopy, dielectric properties can be described over whole frequency by Kramers-Kronig consistent effective functions. The conductivity is dominated two contributions: a Drude-component starting low plasmon near-infrared...
Upon introducing charge carriers into the copper-oxygen sheets of enigmatic lamellar cuprates, ground state evolves from an insulator to a superconductor and eventually seemingly conventional metal (a Fermi liquid). Much has remained elusive about nature this evolution peculiar metallic at intermediate hole-carrier concentrations (p). The planar resistivity unconventional exhibits linear temperature dependence (ρ ∝ T) that is disrupted upon cooling toward superconducting by opening partial...
Stuck in the middle with you: The spherical cluster {(Mo)Mo5}12Cr30 (1) fills, its spin, a gap series of analogous Fe (S=5/2) and V (S=1/2) clusters. This allows deeper understanding magnetic properties members, particularly reference to geometric frustration, also found famous Kagomé lattices. clusters can be considered as coordination polymers periodicity which contain unique pentagonal molybdenum oxide based ligands.
If a metal film, thick enough to be totally opaque, is perforated by tiny subwavelength holes in an orderly fashion, the transmission will enhanced extraordinarily [T. W. Ebbesen, Nature (London) 391, 667 (1998)]. Here, we investigate through ultrathin semitransparent Au film with square array of and observe opposite behavior: less light transmitted pierced compared closed film.
Infrared reflectivity measurements on 122 iron-pnictides reveal the existence of two electronic subsystems. The one gapped due to spin-density-wave transition in parent materials, such as EuFe$_2$As$_{2}$, is responsible for superconductivity doped compounds, like Ba(Fe$_{0.92}$Co$_{0.08})_2$As$_{2}$ and Ba(Fe$_{0.95}$Ni$_{0.05})_2$As$_{2}$. Analyzing dc resistivity scattering rate this contribution, a hidden $T^2$ dependence found, indicating that evolves out Fermi-liquid state. second...
Superconductivity in organic conductors is often tuned by the application of chemical or external pressure. With this type tuning, orbital overlaps and electronic bandwidths are manipulated, whilst properties molecular building blocks remain virtually unperturbed.Here, we show that excitation local vibrations charge-transfer salt $\kappa-(BEDT-TTF)_2Cu[N(CN)_2]Br$ induces a colossal increase carrier mobility opening superconducting-like optical gap. Both features track density...
We measured the optical reflectivity of [001]-oriented $n$-doped ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$ in a broad frequency range (50--22 000 ${\mathrm{cm}}^{\ensuremath{-}1}$) for temperatures from 10 to 300 K. The conductivity, $\ensuremath{\sigma}(\ensuremath{\omega})={\ensuremath{\sigma}}_{1}(\ensuremath{\omega})+\mathrm{i}{\ensuremath{\sigma}}_{2}(\ensuremath{\omega})$, is isotropic within (001) plane; its real part follows power law,...
The development of the fundamental superconducting (SC) energy scales---the SC gap $\mathrm{\ensuremath{\Delta}}$ and superfluid stiffness $J$---of granular aluminum, i.e., thin films composed coupled nanograins, is studied by means optical THz spectroscopy. Starting from well-coupled grains, grows as grains are progressively decoupled, causing unconventional increase ${T}_{c}$ with sample resistivity. When grain coupling suppressed further, saturates while critical temperature decreases,...
Temperature-dependent reflectivity measurements on the kagome metal ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$ in a broad frequency range of $50\ensuremath{-}20\phantom{\rule{0.16em}{0ex}}000\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ down to $T$=10 K are reported. The charge-density wave (CDW) formed below ${T}_{\mathrm{CDW}}$ = 94 manifests itself prominent spectral-weight transfer from low higher energy regions. CDW gap 60--75 meV is observed at lowest temperature and shows...
A gapped spin liquid Quantum liquids avoid conventional magnetic ordering down to the lowest temperatures. Among candidates for this state of matter, organic salts such as κ-(BEDT-TTF) 2 Cu (CN) 3 have been prominent. Miksch et al. studied material using electron resonance elucidate nature its ground state. Instead expected gapless state, temperature dependence susceptibility suggests formation a gap. Science , issue p. 276