A5083260915- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Rare-earth and actinide compounds
- Advanced Thermoelectric Materials and Devices
- Magnetic and transport properties of perovskites and related materials
- Iron-based superconductors research
- Thermal Radiation and Cooling Technologies
- Graphene research and applications
- Thermal properties of materials
- Electronic and Structural Properties of Oxides
- Inorganic Fluorides and Related Compounds
- Carbon Nanotubes in Composites
- Advanced Chemical Physics Studies
- High-pressure geophysics and materials
- Boron and Carbon Nanomaterials Research
- Gas Dynamics and Kinetic Theory
- Crystal Structures and Properties
- Fusion materials and technologies
- Cold Atom Physics and Bose-Einstein Condensates
- Silicon Nanostructures and Photoluminescence
- Ion channel regulation and function
- Nuclear Materials and Properties
- Topological Materials and Phenomena
- Ion Channels and Receptors
- Advanced Energy Technologies and Civil Engineering Innovations
Brookhaven National Laboratory
2019-2025
University of Michigan–Ann Arbor
2013-2018
Tufts University
2012-2013
We investigate the effects of Hund's coupling on resonant x-ray absorption spectra recently discovered family layered nickelate superconductors. contrast two scenarios depending relative strength ratio effective <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mo>(</a:mo><a:msub><a:mi>J</a:mi><a:mi>H</a:mi></a:msub><a:mo>)</a:mo></a:math> to crystal fields <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mo>(</b:mo><b:mi mathvariant="normal">Δ</b:mi><b:mo>)</b:mo></b:math> in...
We present an optimized synthetic method for Sm2Ru3Sn5 and investigate its physical properties electronic structure. was prepared by arc‐melting stoichiometric ratios of the elements confirmed single crystal powder X‐ray diffraction. An antiferromagnetic transition observed at TN = 3.8 K. A modified Curie‐Weiss fit to data in range 50 ‐ 150 K yielded a temperature: θCW ‐36.6 effective magnetic moment: μeff 0.83 μB, agreement with Sm3+ oxidation state. Field‐dependent magnetization up H 7 T...
Abstract The recent and exciting discovery of superconductivity in the hole-doped infinite-layer nickelate Nd 1− δ Sr NiO 2 draws strong attention to correlated quantum materials. From a theoretical view point, this class unconventional superconducting materials provides an opportunity unveil physics hidden Here we study temperature doping dependence local spectrum as well charge, spin orbital susceptibilities from first principles. By using ab initio LQSGW+DMFT methodology, show that onsite...
Here we analyze the divergences of irreducible vertex function in dynamical mean field theory, which may indicate either a nonphysical breakdown perturbation theory or response to some physical phenomenon. To investigate this question, construct quasiparticle from diverging functions. This describes scattering between quasiparticles and quasiholes Fermi liquid. We show that quasparticle does not diverge charge channel, wherein diverge; spin diverge. divergence occurs at Mott transition,...
Here, we review the history and progress of solid-state heat harvesting. Efficiency models, material metrics, current research are discussed for thermoelectrics, thermionics, laser-coolers, modern technologies. Then, discuss nonequilibrium optical phonon harvest in phonovoltaic cell. We make an effort to distinguish between equilibrium heat, or thermal-electricity, targetted a particular mode, phonoelectricity. survey state research, focusing on materials, electron-phonon coupling, entropy...
The recent and exciting discovery of superconductivity in the hole-doped infinite-layer nickelate Nd 1-{\delta} Sr {\delta} NiO 2 draws strong attention to correlated quantum materials. From a theoretical view point, this new class unconventional superconducting materials provides an opportunity unveil physics Here we study temperature doping dependence local spectrum as well charge, spin orbital susceptibilities from first principles. By using ab initio LQSGW+DMFT methodology, show that...
We assess the accuracy of ghost-rotationally-invariant slave-boson (g-RISB) theory in multiorbital systems by applying it to both three-orbital degenerate Hubbard model and a realistic ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$ extracted from first-principle simulations comparing results those obtained using dynamical mean-field (DMFT). Our findings indicate that g-RISB's can be systematically improved toward exact DMFT limit infinite-dimensional models increasing number ghost orbitals. This...
The phonovoltaic (pV) cell is similar to the photovoltaic. It harvests nonequilibrium (hot) optical phonons $({E}_{p,\mathrm{O}})$ more energetic than band gap $(\mathrm{\ensuremath{\Delta}}{E}_{e,g})$ generate power in a p-n junction. We examine theoretical electron-phonon and phonon-phonon scattering rates, Boltzmann transport of electrons, diode equation hydrodynamic simulations describe operation pV develop an analytic model predicting its efficiency. Our findings indicate that material...
An efficient phonovoltaic (pV) material requires a highly energetic optical phonon $({E}_{p,\mathrm{O}}\ensuremath{\gg}{k}_{\mathrm{B}}T)$ with linewidth dominated by the electron-phonon (e-p) coupling and resonant its electronic band gap $(\mathrm{\ensuremath{\Delta}}{E}_{e,g})$, as discussed in Paper I [C. Melnick M. Kaviany, Phys. Rev. B 93, 094302 (2016)]. No current combines these properties. While graphite (graphene) has former two, it lacks gap. Opening tuning is challenging due to...
We show that hot phonons emitted in energy conversion or resistive processes can be converted to electric potential heterobarrier structures. Using phonon and electron interaction kinetics self-consistent ensemble Monte Carlo, we find the favorable conditions for unassisted absorption of design graded heterobarriers their direct into energy. Tandem barriers with nearly optical-phonon height allow substantial gain without current loss. 19$%$ harvested an optimized...
The effects of hydrodynamic and thermal slip on heat transfer in a thermally developing, steady, laminar Couette flow are investigated. Fluid temperature at the inlet to parallel plate channel is prescribed, as various combinations isothermal adiabatic boundary conditions along its surfaces. Analytical expressions incorporating arbitrary developed for profiles, developing fully Nusselt numbers. results relevant liquid gas flows presence apparent molecular slip, respectively.
Thermoelectric modules (TEMs) are used to precisely maintain the setpoint temperature of photonic components generating variable heat loads under varying ambient conditions. The non-component side TEMs is mounted onto conventional sinks (CHSs). At any combination temperature, load and there a unique thermal resistance between TEM corresponding minimal power consumption. Indeed, zero sink minimizes consumption when operates in refrigeration mode, but it heating mode relatively high one...
The phonovoltaic cell harvests optical phonons like a photovoltaic photons, that is, nonequilibrium (hot) population of (at temperature ${T}_{p,\mathrm{O}}$) more energetic than the band gap produces electron-hole pairs in $p\text{\ensuremath{-}}n$ junction, which separates these to produce power. A material requires an phonon mode its and much thermal energy $({E}_{p,\mathrm{O}}>\mathrm{\ensuremath{\Delta}}{E}_{e,g}\ensuremath{\gg}{k}_{\mathrm{B}}T)$, relaxes by generating electrons power...
We investigate the effects of Hund's coupling on resonant X-ray absorption spectra recently discovered family layered nickelate superconductors. contrast two scenarios depending relative strength ratio effective ($J_H$) to crystal fields ($\Delta$) in these systems. carry out cluster and DFT+DMFT simulations RIXS signal at Ni $L$-edge for different values coupling. find latter dominates parent compound while former becomes important sufficiently large doping. Our results are consistent with...
A new heat harvester, the phonovoltaic (pV) cell, was recently proposed. The device converts optical phonons into power before they become heat. Due to low entropy of a typical hot phonon population, can operate at high fractions Carnot limit and harvest more efficiently than conventional harvesting technologies such as thermoelectric generator. Previously, source presumed produce with single polarization momentum. Here, we examine realistic in potential pV application effects this has on...
The interplay between crystal electric field splitting of d states and Hund's rule exchange energy in cobalt-based perovskites offers a promising avenue for inducing spin-state transitions. This study reports new body-centered tetragonal (BCT) phase BaCoO$_3$ (BCT-BaCoO$_3$), synthesized under high pressure (15 GPa) temperature (1200 {\deg}C) conditions. BCT-BaCoO$_3$ adopts double perovskite structure EuTiO$_3$-type (space group I4/mcm, #140), confirmed by high-resolution scanning...
α-voltaics harvest electron-hole pairs created as energetic α particles collide with and ionize electrons in a semiconductor, creating δ-rays. After ionization, charged pair production continues through δ-ray impact ionization events the Auger relaxation of core-shell holes K-shell events. Secondary are quantified using TPP-2M model, fraction is determined energy-loss Coulomb-repulsion perturbed-stationary-state relativistic theory, resulting treated fully ab initio approach multiple Fermi...
We present a charge self-consistent density functional theory combined with the ghost-rotationally-invariant slave-boson (DFT+gRISB) formalism for studying correlated materials. This method is applied to SrVO$_3$ and NiO, representing prototypical metals charge-transfer insulators. For SrVO$_3$, we demonstrate that DFT+gRISB yields an accurate equilibrium volume effective mass close experimentally observed values. Regarding enables simultaneous description of transfer Mott-Hubbard bands,...
We study the interplay of structural phase transition, flat electronic band dispersion, and metal-to-insulator transition (MIT) in parent compounds Ru-pnictide superconductors by using first-principles calculations. Our electron phonon calculations reveal that Ru(P,As) undergo MIT accompanied orthorhombic to monoclinic distortion at low temperature, but RuSb stays metallic agreement with experimental findings. It is demonstrated correlation, as treated DFT+U, DFT+Gutzwiller, dynamical...