A5101583166- Physics of Superconductivity and Magnetism
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Semiconductor Quantum Structures and Devices
- Quantum Dots Synthesis And Properties
- Strong Light-Matter Interactions
- Spectroscopy and Quantum Chemical Studies
- Dark Matter and Cosmic Phenomena
- Methane Hydrates and Related Phenomena
- Advanced Semiconductor Detectors and Materials
- Chalcogenide Semiconductor Thin Films
- Semiconductor materials and interfaces
- Thermal Radiation and Cooling Technologies
- Advanced Thermoelectric Materials and Devices
- Solid-state spectroscopy and crystallography
- Particle accelerators and beam dynamics
- Superconductivity in MgB2 and Alloys
- Quantum, superfluid, helium dynamics
- Magnetic properties of thin films
- Quantum and electron transport phenomena
- Advanced Chemical Physics Studies
- Multiferroics and related materials
- Laser-Matter Interactions and Applications
- Astro and Planetary Science
- Thermal properties of materials
University of Colorado Boulder
2021-2024
Max Planck Institute for the Structure and Dynamics of Matter
2024
Tata Institute of Fundamental Research
1994-1995
The dynamics of hot carriers has been investigated extensively for III-V compound semiconductors in the past but not as well II-VI semiconductors. In this paper, we calculate electron and hole energy-loss rates (ELR's) CdSe taking into account all relevant phonon emission processes. Interband intraband scattering two uppermost valence bands (A B) are included. We make a detailed comparison these ELR's with those GaAs. then report our experimental measurements time- energy-resolved...
Signatures of photoinduced superconductivity have been reported in cuprate materials subjected to a coherent phonon drive. A “cold” superfluid was extracted from the transient Terahertz conductivity and seen coexist with “hot” uncondensed quasiparticles, hallmark driven-dissipative system which interplay between incoherent responses is not well understood. Here, time resolved spontaneous Raman scattering used probe lattice temperature superconducting state <a:math...
We have grown and characterized (110)-oriented YBa2Cu3O7−x (YBCO)/PrBa2(Cu0.8Ga0.2)3O7−x (PBCGO) bilayer YBCO/PBCGO/YBCO trilayer heterostructures, which were deposited by pulsed laser deposition technique for the nanofabrication of YBCO-based superconductor (S)/insulator (I)/superconductor (S) tunneling vertical geometry Josephson junction other electronic devices. The structural properties these investigated through various x-ray diffraction techniques (profile, reflectivity, pole figure,...
We obtain hot-carrier cooling rates in CdSe using upconversion luminescence with 2.5-psec time resolution. The carrier energy-loss are significantly reduced comparison those expected a simple theory of energy transfer to the lattice. slow can be explained caused by hot-phonon effects provided that lattice dynamical lifetime optical phonons is about 6 ps at 8 K.
In spin-$\frac{1}{2}$ Mott insulators, nonmagnetic quantum liquid phases are often argued to arise when the system shows no magnetic ordering, but identifying positive signatures of these or related spinon quasiparticles can be elusive. Here, we use Raman scattering provide three for spinons in a possible spin-orbit material $\mathrm{Ba}{}_{4}\mathrm{Ir}{}_{3}\mathrm{O}{}_{10}$: (1) broad hump, which show from Luttinger with parallel photon polarizations normal one-dimensional chains; (2)...
Time resolved measurements provide a new way to disentangle complex interactions in quantum materials due their different timescales. We used pump-probe Raman scattering investigate the apical oxygen vibration YBa$_2$Cu$_3$O$_{6+x}$ under nonequilibrium conditions. Time-dependence of phonon population demonstrated strong electron-phonon coupling. Most importantly, shifts higher energy transient smearing Fermi surface remarkable agreement with diagrammatic theory. also discuss insights into...
In the search for high-performance thermoelectrics, materials such as clathrates have drawn attention due to having both glasslike low phonon thermal conductivity and crystal-like high electrical conductivity. ${\mathrm{Ba}}_{8}{\mathrm{Ga}}_{16}{\mathrm{Ge}}_{30}$ (BGG) has a loosely bound guest Ba atom trapped inside rigid Ga-Ge cage structures. Avoided crossings between acoustic phonons flat branches been proposed be source of lattice BGG. site disorder with Ga Ge exchanging places in...
We measure the time- and energy-resolved luminescence due to hot biexcitons in CdSe at 8 K using picosecond upconversion spectroscopy. The biexciton rises with a time constant of 12 ps following photoexcitation electrons holes. It then decays 240 ps. dependent spectrum is used deduce energy relaxation rates CdSe. compare results theoretical calculations based on phonon emission by biexcitons.
We demonstrate an approach to the structural and electronic property modification of perovskites, focusing on ${\mathrm{Pr}}_{2}\mathrm{Cu}{\mathrm{O}}_{4}$, undoped parent compound a class electron-doped copper-oxide superconductors. Currents were passed parallel or perpendicular copper oxygen layers with voltage ramped up until rapid drop in resistivity was achieved, process referred as ``flash.'' The current then further increased tenfold current-control mode. This state quenched by...
Band-edge luminescence in photoexcited CdSe is known to show several interesting features due radiative decay of free and bound excitons excitonic molecules (biexcitons). In this paper, we report our experiments on the study time evolution some these processes CdSe, using up-conversion spectroscopy with a resolution 2.5 ps. We obtain time-dependent spectra at two e$hyh pair excitation densities (estimated be ${\mathit{n}}_{0}$=8\ifmmode\times\else\texttimes\fi{}${10}^{16}$...