A5083251129- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Electronic and Structural Properties of Oxides
- Quantum and electron transport phenomena
- Superconductivity in MgB2 and Alloys
- Iron-based superconductors research
- Superconducting Materials and Applications
- Rare-earth and actinide compounds
- Magnetic properties of thin films
- Theoretical and Computational Physics
- Organic and Molecular Conductors Research
- Semiconductor materials and devices
- Quantum, superfluid, helium dynamics
- Quantum Electrodynamics and Casimir Effect
- Cold Atom Physics and Bose-Einstein Condensates
- ZnO doping and properties
- Inorganic Fluorides and Related Compounds
- Quantum many-body systems
- Advanced Thermodynamics and Statistical Mechanics
- Cosmology and Gravitation Theories
- Quantum Mechanics and Applications
- High-pressure geophysics and materials
- Surface and Thin Film Phenomena
- Magnetic Properties and Applications
Sapienza University of Rome
2015-2024
Institute for Complex Systems
2015-2024
Istituto Nazionale di Fisica Nucleare, Sezione di Roma I
2016-2024
Istituto di Sessuologia Clinica
2019-2023
Istituto Nazionale di Fisica Nucleare
2022-2023
ORCID
2021
National Interuniversity Consortium for the Physical Sciences of Matter
2009-2019
Bellingham Technical College
2018
Istituto Nazionale di Fisica Nucleare, Sezione di Napoli
2016
Donostia International Physics Center
2009-2012
Charge density waves are a common occurrence in all families of high critical temperature superconducting cuprates. Although consistently observed the underdoped region phase diagram and at relatively low temperatures, it is still unclear to what extent they influence unusual properties these systems. Using resonant x-ray scattering we carefully determined dependence charge modulations (Y,Nd)Ba$_2$Cu$_3$O$_{7-{\delta}}$ for three doping levels. We discovered short-range dynamical...
Resonances in the superconducting properties, a regime of crossover from BCS to mixed Bose-Fermi superconductivity, are investigated two-band superconductor where chemical potential is tuned near band edge second mini-band generated by quantum confinement effects. The shape resonances at T=0 gaps (belonging class Feshbach-like resonances) manifested interference effects gap first large Fermi surface when proximity mini-band. case superlattice wells considered and amplification...
Abstract The recent development in the fabrication of artificial oxide heterostructures opens new avenues field quantum materials by enabling manipulation charge, spin and orbital degrees freedom. In this context, discovery two-dimensional electron gases (2-DEGs) at LaAlO 3 /SrTiO interfaces, which exhibit both superconductivity strong Rashba spin-orbit coupling (SOC), represents a major breakthrough. Here, we report on realisation field-effect device, whose physical properties, including...
Abstract The universality of the strange metal phase in many quantum materials is often attributed to presence a critical point (QCP), zero-temperature transition ruled by fluctuations. In cuprates, where superconductivity hinders direct QCP observation, indirect evidence comes from identification fluctuations compatible with phase. Here we show that recently discovered charge density (CDF) possess right properties be associated transition. Using resonant x-ray scattering, studied CDF two...
In the last few years charge density waves (CDWs) have been ubiquitously observed in high-temperature superconducting cuprates and are now most investigated among competing orders still hot debate on these systems. A wealth of new experimental data raise several fundamental issues that challenge various theoretical proposals. Here, we account for complex temperature vs. doping phase diagram provide a coherent scenario explaining why different CDW onset curves by probes seem to extrapolate at...
Oxide heterostructures are of great interest both for fundamental and applicative reasons. In particular the two-dimensional electron gas at LaAlO$_3$/SrTiO$_3$ or LaTiO$_3$/SrTiO$_3$ interfaces displays many different physical properties functionalities. However there clear indications that interface electronic state is strongly inhomogeneous therefore it crucially relevant to investigate possible intrinsic mechanisms underlying this inhomogeneity. Here electrostatic potential confining...
Abstract Besides the mechanism responsible for high critical temperature superconductivity, grand unresolved issue of cuprates is occurrence a strange metallic state above so-called pseudogap T * . Even though such has been successfully described within phenomenological scheme, Marginal Fermi-Liquid theory, microscopic explanation still missing. However, recent resonant X-ray scattering experiments identified new class charge density fluctuations characterized by low characteristic energies...
Within the Hubbard-Holstein model, we evaluate crossover lines marking opening of pseudogaps in cuprates, which, our scenario, are ruled by proximity to a charge-ordering quantum criticality (stripe formation). We find that their isotopic dependence, due critical fluctuations, implies substantial positive shift pseudogap-formation temperature T(*). infer superconducting T(c) is nearly absent optimally and overdoped regimes negative increasing upon underdoping. The dynamical nature transition...
We consider a model for the two-dimensional electron gas formed at interface of oxide heterostructures, which includes Rashba spin-orbit coupling proportional to electric field perpendicular interface. Based on standard mechanism polarity catastrophe, we assume that is density. Under these simple and general assumptions, show phase separation instability occurs realistic values band parameters. This could provide an intrinsic recently observed inhomogeneous phases LaAlO_3/SrTiO_3 or...
The two-dimensional electron gas at the LaTiO${}_{3}$/SrTiO${}_{3}$ or LaAlO${}_{3}$/SrTiO${}_{3}$ oxide interfaces becomes superconducting when carrier density is tuned by gating. measured resistance and superfluid reveal an inhomogeneous superconductivity resulting from percolation of filamentary structures ``puddles'' with randomly distributed critical temperatures, embedded in a nonsuperconducting matrix. Following evidence that related to appearance high-mobility carriers, we model...
The normal state of optimally doped cuprates is dominated by the "strange metal" phase that shows a linear temperature ($T$) dependence resistivity persisting down to lowest $T$. For underdoped this behavior lost below pseudogap $T^*$, where Charge Density Waves (CDW) together with other intertwined local orders characterize ground state. Here we show $T$-linear highly strained, ultrathin and YBa$_2$Cu$_3$O$_{7-\delta}$ films restored when CDW amplitude, detected Resonant Inelastic X-ray...
Abstract Anomalous metallic properties are often observed in the proximity of quantum critical points, with violation Fermi Liquid paradigm. We propose a scenario where, near point, dynamical fluctuations order parameter finite correlation length mediate nearly isotropic scattering among quasiparticles over entire surface. This produces strange behavior, which is extended to lowest temperatures by an increase damping fluctuations. phenomenologically identify one single ruling this increasing...
The experimental determination of the quantum critical point (QCP) that triggers self-organization charged striped domains in cuprate perovskites is reported. phase diagram doped superconductors determined by a first variable, hole doping δ, and second micro-strain ε Cu-O bond length, obtained from Cu K-edge extended x-ray absorption fine structure. For fixed optimum doping, δc = 0.16, we show presence QCP for onset local lattice distortions stripe formation at εc. temperature Tc(ε,δ)...
We investigate the effects of mesoscopic inhomogeneities on metal-superconductor transition occurring in several two-dimensional electron systems. Specifically, as a model systems with inhomogeneities, we consider random-resistor network, which solve both an exact numerical approach and by effective medium theory. find that width these superconductors is mainly ruled disorder rather than fluctuations. also "tail" features resistivity curves interfaces between LaAlO3 or LaTiO3 SrTiO3 can...
The multigap superconductivity modulated by quantum confinement effects in a superlattice of wells is presented.Our theoretical BCS approach captures the low-energy physics shape resonance superconducting gaps when chemical potential tuned near Lifshitz transition.We focus on case weak Cooper-pairing coupling channels and strong pair exchange interaction driven repulsive Coulomb that allows to use theory weakcoupling regime neglecting retardation like condensates ultracold gases.The...
The microscopic nature of an insulating state in the vicinity a superconducting state, presence disorder, is hotly debated question. While simplest scenario proposes that Coulomb interactions destroy Cooper pairs at transition, leading to localization single electrons, alternate possibility supported by experimental observations suggests instead directly localize. question homogeneity, granularity, or possibly glassiness material on verge this transition intimately related fundamental issue....
The large diversity of exotic electronic phases displayed by two-dimensional superconductors confronts physicists with new challenges. These include the recently discovered quantum Griffith singularity in atomic Ga films, topological proximized insulators and unconventional Ising pairing transition metal dichalcogenide layers. In LaAlO3/SrTiO3 heterostructures, a gate tunable superconducting electron gas is confined well at interface between two insulating oxides. Remarkably, coexists both...
The spin galvanic effect (SGE) describes the conversion of a nonequilibrium polarization into transverse charge current. Recent experiments have demonstrated large efficiency for two-dimensional electron gas formed at interface between two insulating oxides, LaAlO_{3} and SrTiO_{3}. Here, we analyze SGE oxide interfaces within three-band model Ti t_{2g} orbitals which displays an interesting variety effective spin-orbit couplings in individual bands that contribute differently to spin-charge...
One of the hallmarks Berezinskii-Kosterlitz-Thouless (BKT) transition in two-dimensional (2D) superconductors is universal jump superfluid density, that can be indirectly probed via non-linear exponent current-voltage $IV$ characteristics. Here, we compare experimental measurements characteristics two cases, namely NbN thin films and SrTiO$_3$-based interfaces. While former display a paradigmatic example BKT-like effects, latter do not seem to justify BKT analysis. Rather, observed well...
The derivation of the effective theory for phase degrees freedom in a superconductor is still, to some extent, an open issue. It commonly assumed that classical $\mathrm{XY}$ model and its quantum generalizations can be exploited as phase-only models. In regime, however, this assumption leads spurious results, such violation Galilean invariance continuum model. Starting from general microscopic model, paper we explicitly derive low-energy phase, up fourth-order terms. This expansion allows...