A5039357269- Physics of Superconductivity and Magnetism
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Electronic and Structural Properties of Oxides
- Magnetic properties of thin films
- Iron-based superconductors research
- Superconducting Materials and Applications
- Superconductivity in MgB2 and Alloys
- Theoretical and Computational Physics
- Quantum and electron transport phenomena
- Organic and Molecular Conductors Research
- ZnO doping and properties
- Ferroelectric and Piezoelectric Materials
- Rare-earth and actinide compounds
- Magnetism in coordination complexes
- Catalytic Processes in Materials Science
- Multiferroics and related materials
- High-pressure geophysics and materials
- Quantum, superfluid, helium dynamics
- Advanced Chemical Physics Studies
- Copper-based nanomaterials and applications
- Superconducting and THz Device Technology
- Advancements in Solid Oxide Fuel Cells
- Magneto-Optical Properties and Applications
- Semiconductor materials and devices
Max Planck Institute for Solid State Research
2016-2025
Institute for Microelectronics and Microsystems
2024
National Research Council
2024
Università di Camerino
2024
Institute of Crystallography
2024
Rome International Center for Materials Science
2024
Brookhaven National Laboratory
2005-2023
Cornell University
2021
Auburn University
2021
Center for Integrated Quantum Science and Technology
2021
The report that T(c) was doubled in underdoped La2-xSrxCuO4 films under compressive epitaxial strain has stirred great interest. We show such are extremely sensitive to oxygen intake, even at very low temperature, with startling consequences including colossal lattice expansion and a crossover from semiconductor metallic behavior. can bring up 40 K La2CuO4 on SrTiO3 substrates-without any Sr doping tensile strain. On LaSrAlO4 substrates, we reached T(c)=51.5 K, the highest so far La2-xSrxCuO4.
The question of how thin cuprate layers can be while still retaining high-temperature superconductivity (HTS) has been challenging to address, in part because experimental studies require the synthesis near-perfect ultrathin HTS and ways profile superconducting properties such as critical temperature superfluid density across interfaces with atomic resolution. We used atomic-layer molecular beam epitaxy synthesize bilayers a metal (La(1.65)Sr(0.45)CuO4) insulator (La2CuO4) which each layer...
Nonequilibrium phase transitions, which are defined by the formation of macroscopic transient domains, optically dark and cannot be observed through conventional temperature- or pressure-change studies. We have directly determined structural dynamics such a nonequilibrium transition in cuprate superconductor. Ultrafast electron crystallography with use tilted optical geometry technique afforded necessary atomic-scale spatial temporal resolutions. The behavior displays notable "structural...
We have used resonant x-ray diffraction to develop a detailed description of antiferromagnetic ordering in epitaxial superlattices based on two-unit-cell thick layers the strongly correlated metal LaNiO3. also report reference experiments thin films PrNiO3 and NdNiO3. The resulting data indicate spiral state whose polarization plane can be controlled by adjusting Ni d-orbital occupation via two independent mechanisms: strain spatial confinement valence electrons. are discussed light recent...
A combined analysis of x-ray absorption and resonant reflectivity data was used to obtain the orbital polarization profiles superlattices composed four-unit-cell-thick layers metallic LaNiO3 insulating RXO3 (R=La, Gd, Dy X=Al, Ga, Sc), grown on substrates that impose either compressive or tensile strain. This superlattice geometry allowed us partly separate influence epitaxial strain from interfacial effects controlled by chemical composition blocking layers. Our quantitative reveal...
Abstract In high-energy physics, the Higgs field couples to gauge bosons and fermions gives mass their elementary excitations. Experimentally, such couplings can be inferred from decay product of boson, i.e., scalar (amplitude) excitation field. superconductors, Cooper pairs bear a close analogy Interaction between other degrees freedom provides dissipation channels for amplitude mode, which may reveal important information about microscopic pairing mechanism. To this end, we investigate...
We have used polarized Raman scattering to probe lattice vibrations and charge ordering in 12 nm thick, epitaxially strained PrNiO$_3$ films, superlattices of with the band-insulator PrAlO$_3$. A carefully adjusted confocal geometry was eliminate substrate contribution spectra. In films under tensile strain, which undergo a metal-insulator transition upon cooling, spectra reveal phonon modes characteristic ordering. These anomalous phonons do not appear compressively remain metallic at all...
Ultrafast optical control of quantum systems is an emerging field physics. In particular, the possibility light-driven superconductivity has attracted much attention. To identify nonequilibrium superconductivity, it necessary to measure fingerprints on ultrafast timescales. Recently, nonlinear THz third-harmonic generation (THG) was shown directly probe collective degrees freedoms superconducting condensate, including Higgs mode. Here, we extend this idea states in La
Abstract The polarity of a surface can affect the electronic and structural properties oxide thin films through electrostatic effects. Understanding mechanism behind these effects requires knowledge atomic structure characteristics at surface. In this study, we use annular bright-field imaging to investigate Pr 0.8 Sr 0.2 NiO 2+ x (0 < 1) film. We observe polar distortion coupled with octahedral rotations in fully oxidized 3 sample, stronger partially reduced sample. Its spatial depth...
In most anisotropic compounds such as bismuth-based layered cuprate perovskites, the supercurrent across blocking layer is of Josephson type, and a single crystal forms natural stack junctions. Here, we report on evidence Josephson-like transport in an artificial superlattice composed 10 LaSrCuO–LaCuO repeats, creating junctions, where LCO superconducting Mott insulator LSCO overdoped metal. The has been designed with long period d = L + W 5.28 nm, being thicknesses units, respectively,...
The family of infinite-layer nickelates promises important insights into the mechanism unconventional superconductivity. Since superconductivity has so far only been observed in epitaxial thin films, heteroepitaxy with substrate or a capping layer possibly plays an role. Here, we use soft x-ray spectroscopy to investigate superlattices as potential approach for targeted material design high-temperature superconductors. We observe modulations valence state and oxygen coordination...
Using an advanced molecular beam epitaxy system, we have reproducibly synthesized atomically smooth films of high-temperature superconductors and uniform trilayer junctions with virtually perfect interfaces. We found that supercurrent runs through very thick barriers. can rule out pinholes microshorts; this "giant proximity effect" (GPE) is intrinsic. It defies the conventional explanation; it might originate in resonant tunneling pair states almost-superconducting barrier. GPE may also be...
We use resonant soft x-ray scattering (RSXS) to quantify the hole distribution in a superlattice of insulating La2CuO4 (LCO) and overdoped La2-xSrxCuO4 (LSCO). Despite its nonsuperconducting constituents, this structure is superconducting with T_{c}=38 K. found that conducting holes redistribute electronically from LSCO LCO layers. The layers were be optimally doped, suggesting they are main drivers superconductivity. Our results demonstrate utility RSXS for separating electronic structural...
Abstract Cuprate high- T c superconductors are known for their intertwined interactions and the coexistence of competing orders. Uncovering experimental signatures these is often first step in understanding complex relations. A typical spectroscopic signature interaction between a discrete mode continuum excitations Fano resonance/interference, characterized by asymmetric light-scattering amplitude as function electromagnetic driving frequency. In this study, we report new type resonance...
The essential building blocks of cuprate superconductors are two-dimensional <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>CuO</a:mi><a:mn>2</a:mn></a:msub></a:math> sheets interspersed with charge reservoir layers. In bilayer cuprates, two closely spaced <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msub><b:mi>CuO</b:mi><b:mn>2</b:mn></b:msub></b:math> separated by a larger distance from the subsequent pair in next unit cell. contrast to single-layer prior...
While the search of high-Tc superconductivity was driven mostly by trial and error methodology searching for novel materials, here we provide a quasi-first-principle quantum theory engineering in artificial superlattices (AHTS) with period d, ranging from 5.28 down to 3 nanometers, made superconducting wells variable thickness L.An important feature our design is key role interface internal electric field giving Rashba spin-orbit coupling (SOC) nanoscale building blocks.By tuning geometrical...
The electronic phase behavior and functionality of interfaces surfaces in complex materials are strongly correlated to chemical composition profiles, stoichiometry intermixing. Here a novel analysis scheme for resonant X-ray reflectivity maps is introduced determine such which element specific non-destructive, exhibits atomic-layer resolution probing depth hundreds nanometers.
Abstract The exploitation of interface effects turned out to be a powerful tool for generating exciting material properties. Such properties include magnetism, electronic and ionic transport even superconductivity. Here, instead using conventional homogeneous doping enhance the hole concentration in lanthanum cuprate achieve superconductivity, we replace single LaO planes with SrO dopant atomic-layer-by-layer molecular beam epitaxy (two-dimensional doping). Electron spectroscopy microscopy,...