A5047297890- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Advanced Chemical Physics Studies
- Superconductivity in MgB2 and Alloys
- Iron-based superconductors research
- Magnetic properties of thin films
- Quantum and electron transport phenomena
- Electronic and Structural Properties of Oxides
- High-pressure geophysics and materials
- Inorganic Fluorides and Related Compounds
- Magnetic and transport properties of perovskites and related materials
- Superconducting Materials and Applications
- Quantum Information and Cryptography
- Machine Learning in Materials Science
- Magneto-Optical Properties and Applications
- Surface and Thin Film Phenomena
- Solid-state spectroscopy and crystallography
- Graphene research and applications
- Spacecraft and Cryogenic Technologies
- Advanced Electrical Measurement Techniques
- 2D Materials and Applications
- Atomic and Subatomic Physics Research
- Nuclear Materials and Properties
- Quantum Computing Algorithms and Architecture
- Quantum, superfluid, helium dynamics
University of Rhode Island
2024
Johns Hopkins University Applied Physics Laboratory
2019-2023
University of Colorado Boulder
2008-2014
Lawrence Berkeley National Laboratory
2003-2007
Material Sciences (United States)
2005-2007
University of California, Berkeley
2002-2006
Cornell University
2005-2006
National Institute of Advanced Industrial Science and Technology
2005
The University of Tokyo
2005
Scanning tunneling spectroscopy of the high-Tc superconductor Bi2Sr2CaCu2O8+delta reveals weak, incommensurate, spatial modulations in conductance. Images these energy-dependent are Fourier analyzed to yield dispersion their wavevectors. Comparison dispersions with photoemission data indicates that quasiparticle interference, due elastic scattering between characteristic regions momentum-space, provides a consistent explanation for conductance modulations, without appeal another order...
The randomness of dopant atom distributions in cuprate high-critical temperature superconductors has long been suspected to cause nanoscale electronic disorder. In the superconductor Bi2Sr2CaCu2O8+delta, we identified populations atomic-scale impurity states whose spatial densities follow closely those oxygen atoms. We found that impurity-state locations are strongly correlated with all manifestations This disorder occurs via an unanticipated mechanism exhibiting high-energy spectral weight...
The doping dependence of nanoscale electronic structure in superconducting Bi(2)Sr(2)CaCu(2)O(8 + delta) is studied by scanning tunneling microscopy. At all dopings, the low energy density-of-states modulations are analyzed according to a simple model quasiparticle interference and found be consistent with Fermi-arc superconductivity. coherence peaks, ubiquitous near-optimal spectra, destroyed strong underdoping new spectral type appears. Exclusively regions exhibiting this spectrum, we find...
A universal high energy anomaly in the single particle spectral function is reported three different families of temperature superconductors by using angle-resolved photoemission spectroscopy. As we follow dispersing peak from Fermi to valence band complex, find dispersion anomalies marked two distinctive scales, E1 approximately 0.38 eV and E2 0.8 eV. marks above which splits into branches. One a continuation near parabolic dispersion, albeit with reduced weight, reaches bottom at Gamma...
Many theoretical models of high-temperature superconductivity focus only on the doping dependence CuO(2)-plane electronic structure. However, such are manifestly insufficient to explain strong variations in superconducting critical temperature, T(c), among cuprates that have identical hole density but crystallographically different outside CuO(2) plane. A key challenge, therefore, has been identify a predominant out-of-plane influence controlling superconductivity, with much attention...
In quasi-two-dimensional electron systems of layered transition metal dichalcogenides (TMDs) there is still controversy about the nature transitions to charge-density wave (CDW) phases, i.e., whether they are described by a Peierls-type mechanism or lattice-driven model. By performing scanning tunneling microscopy experiments on canonical TMD-CDW systems, we image electronic modulation and lattice distortion separately in $2\mathrm{H}\text{\ensuremath{-}}\mathrm{Ta}{\mathrm{S}}_{2}$,...
We present scanning tunneling microscopy and spectroscopy experiments on the novel ${J}_{\mathrm{eff}}=1/2$ Mott insulator ${\mathrm{Sr}}_{2}\mathrm{Ir}{\mathrm{O}}_{4}$. Local density of states (LDOS) measurements show an intrinsic insulating gap 620 meV that is asymmetric about Fermi level larger than previously reported values. The size this suggests ${\mathrm{Sr}}_{2}\mathrm{Ir}{\mathrm{O}}_{4}$ likely a rather Slater insulator. In addition, we found small number native defects which...
We use the tomographic density of states (TDOS), which is a measure for single slice through band structure solid, to study temperature evolution superconducting gap in cuprates. The TDOS provides accuracy determining both pair-forming strength $\ensuremath{\Delta}$ and pair-breaking rate $\ensuremath{\Gamma}$. In optimally underdoped Bi${}_{2}$Sr${}_{2}$CaCu${}_{2}$O${}_{8+\ensuremath{\delta}}$, we find near-nodal smoothly evolves transition temperature---clear evidence existence preformed...
Abstract Discovery of novel materials is slow but necessary for societal progress. Here, we demonstrate a closed-loop machine learning (ML) approach to rapidly explore large search space, accelerating the intentional discovery superconducting compounds. By experimentally validating results ML-generated superconductivity predictions and feeding those data back into ML model refine, that success rates superconductor can be more than doubled. Through four cycles, report in Zr-In-Ni system,...
The joint density of states (JDOS) Bi2Sr2CaCu2O8+x is calculated by evaluating the autocorrelation single particle spectral function A(k,omega) measured from angle resolved photoemission spectroscopy (ARPES). These results are compared with Fourier transformed (FT) conductance modulations scanning tunneling microscopy (STM). Good agreement between two experimental probes found for different doping values examined. In addition, comparing FT-STM to autocorrelated ARPES spectra photon...
The cuprates contain a range of nanoscale phenomena that consist both LDOS(E) features and spatial excitations. Many these can only be observed through the use SI-STM their disorder mapped out fitting phenomenological model to LDOS(E). We present study nanometer scale single crystal cryogenically cleaved samples Bi2Sr2CaCu2O8+x whose dopings from p = 0.19 0.06. used is Tripartite has been successfully applied average previously. resulting energy maps show structured patchwork three scales,...
We study the $\tau_1$-impurity induced $\mathbf{q}$-space pattern of energy derivative local density states (LDOS) in a d-wave superconductor. are motivated part by recent scanning tunneling microscopy (STM) observation strong gap inhomogeneity with weak charge variation Bi$_{2}$Sr$_2$CaCu$_2$O$_{8+\delta}$ (BSCCO). The hypothesis is that might be triggered disorder pair potential. focus on effects electron coupling to various bosonic modes, at mode shifted superconducting gap. due highly...
We study the effects of electronic coupling to bosonic modes on scanning tunneling microscopy (STM) into a $d$-wave superconductor. propose investigate these by means different technique: Fourier transformed inelastic electron spectroscopy (FT-IETS). Specifically, in this technique, spectrum energy derivative local density states is addressed, which proportional $({d}^{2}I∕d{V}^{2})(\mathbf{q},eV)$ characteristics measured FT-IETS STM. consider role scattering due boson with specific...
We present and validate a novel method for noise injection of arbitrary spectra in quantum circuits that can be applied to any system capable executing single qubit rotations, including cloud-based processors. As the consequences temporally-correlated on performance algorithms are not well understood, capability engineer inject such systems is paramount. To date, capabilities have been limited highly platform specific, requiring low-level access control hardware. experimentally our universal...
The discovery of novel materials drives industrial innovation, although the pace tends to be slow due infrequency "Eureka!" moments. These moments are typically tangential original target experimental work: "accidental discoveries". Here we demonstrate acceleration intentional - targeting material properties interest while generalizing search a large space with machine learning (ML) methods. We closed-loop ML process superconducting materials, which have applications ranging from quantum...
Predicting the consequences of a major coastal storm is increasingly difficult as result global climate change and growing societal dependence on critical infrastructure (CI). Past storms are no longer reliable predictor future weather events, traditional approach to vulnerability assessment presents accumulated loss in largely quantitative terms that lack specificity local emergency managers need develop effective plans mitigation strategies. The Rhode Island Coastal Hazards Modeling...
We present a phenomenological model that describes the low energy electronic structure of cuprate high temperature superconductor Bi2Sr2CaCu2O8+x as observed by Spectroscopic Imagining Scanning Tunneling Microscopy (SI-STM). Our is based on observations from Quasiparticle Interference (QPI) measurements and Local Density States (LDOS) span range hole densities critical doping, p~0.19, to extremely underdoped, p~0.06. The presented below unifies spectral density states in QPI studies with...
Abstract Here we consider a tunable superconducting cavity that can be used either as coupler to qubit inside the or low noise, temperature, RF filter. Our design consists of an array radio-frequency quantum interference devices (rf SQUIDs) cavity. This forms metamaterial structure which couples through its magnetic plasma frequency. By tuning resonant frequency applied flux, one tune mode profile. allows us detune initially centered at 5.593 GHz by over 200 MHz. The maximum quality factor...