Proximity-Induced Superconductivity in a 2D Kondo Lattice of an -Electron-Based Surface Alloy.

Realizing hybrids of low-dimensional Kondo lattices and superconducting substrates leads to fascinating platforms for studying the exciting physics of strongly correlated electron systems with induced superconducting pairing. Here, we report a scanning tunneling microscopy and spectroscopy study of a new type of two-dimensional (2D) La-Ce alloy grown epitaxially on a superconducting Re(0001) substrate. We observe the characteristic spectroscopic signature of a hybridization gap evidencing the coherent spin screening in the 2D Kondo lattice realized by the ultrathin La-Ce alloy film on normal conducting Re(0001).

Many-Body Majorana Braiding without an Exponential Hilbert Space.

Qubits built out of Majorana zero modes constitute the primary path toward topologically protected quantum computing. Simulating the braiding process of multiple Majorana zero modes corresponds to the quantum dynamics of a superconducting many-body system. It is crucial to study the Majorana dynamics both in the presence of all other quasiparticles and for reasonably large system sizes.

Visualizing the atomic-scale origin of metallic behavior in Kondo insulators.

A Kondo lattice is often electrically insulating at low temperatures. However, several recent experiments have detected signatures of bulk metallicity within this Kondo insulating phase. In this study, we visualized the real-space charge landscape within a Kondo lattice with atomic resolution using a scanning tunneling microscope.

Evidence for dispersing 1D Majorana channels in an iron-based superconductor.

The possible realization of Majorana fermions as quasiparticle excitations in condensed-matter physics has created much excitement. Most studies have focused on Majorana bound states; however, propagating Majorana states with linear dispersion have also been predicted. Here, we report scanning tunneling spectroscopic measurements of crystalline domain walls (DWs) in FeSeTe We located DWs across which the lattice structure shifts by half a unit cell.

Nature of the spin resonance mode in CeCoIn.

Spin-fluctuation-mediated unconventional superconductivity can emerge at the border of magnetism, featuring a superconducting order parameter that changes sign in momentum space. Detection of such a sign-change is experimentally challenging, since most probes are not phase-sensitive. The observation of a spin resonance mode (SRM) from inelastic neutron scattering is often seen as strong phase-sensitive evidence for a sign-changing superconducting order parameter, by assuming the SRM is a spin-excitonic bound state.

Quantum engineered Kondo lattices.

Atomic manipulation techniques have provided a bottom-up approach to investigating the unconventional properties and complex phases of strongly correlated electron materials. By engineering artificial systems containing tens to thousands of atoms with tailored electronic or magnetic properties, it has become possible to explore how quantum many-body effects emerge as the size of a system is increased from the nanoscale to the mesoscale. Here we investigate both theoretically and experimentally the quantum engineering of nanoscale Kondo lattices - Kondo droplets - exemplifying nanoscopic replicas of heavy-fermion materials.

Josephson Scanning Tunneling Spectroscopy in d_{x^{2}-y^{2}}-Wave Superconductors: A Probe for the Nature of the Pseudogap in the Cuprate Superconductors.

Recent advances in the development of Josephson scanning tunneling spectroscopy (JSTS) have opened a new path for the exploration of unconventional superconductors. We demonstrate that the critical current I_{c}, measured via JSTS, images the spatial form of the superconducting order parameter in d_{x^{2}-y^{2}}-wave superconductors around defects and in the Fulde-Ferrell-Larkin-Ovchinnikov state. Moreover, we show that I_{c} probes the existence of phase-incoherent superconducting correlations in the pseudogap region of the cuprate superconductors, thus providing unprecedented insight into its elusive nature.

Atomic-scale interface engineering of Majorana edge modes in a 2D magnet-superconductor hybrid system.

Topological superconductors are predicted to harbor exotic boundary states-Majorana zero-energy modes-whose non-Abelian braiding statistics present a new paradigm for the realization of topological quantum computing. Using low-temperature scanning tunneling spectroscopy, here, we report on the direct real-space visualization of chiral Majorana edge states in a monolayer topological superconductor, a prototypical magnet-superconductor hybrid system composed of nanoscale Fe islands of monoatomic height on a Re(0001)-O(2 × 1) surface. In particular, we demonstrate that interface engineering by an atomically thin oxide layer is crucial for driving the hybrid system into a topologically nontrivial state as confirmed by theoretical calculations of the topological invariant, the Chern number.

Equivalent Resistance from the Quantum to the Classical Transport Limit.

We generalize the concept of equivalent resistance to the entire range from coherent quantum to diffusive classical transport by introducing the notion of transport equivalent networks. We show that this novel concept presents us with a platform to simplify the structure of quantum networks while preserving their global and local transport properties, even in the presence of electron-phonon or electron-electron interactions. This allows us to describe the evolution of equivalent quantum networks to equivalent classical resistor networks with increasing interaction strength.

Theory of scanning tunneling spectroscopy: from Kondo impurities to heavy fermion materials.

Kondo systems ranging from the single Kondo impurity to heavy fermion materials present us with a plethora of unconventional properties whose theoretical understanding is still one of the major open problems in condensed matter physics. Over the last few years, groundbreaking scanning tunneling spectroscopy (STS) experiments have provided unprecedented new insight into the electronic structure of Kondo systems. Interpreting the results of these experiments-the differential conductance and the quasi-particle interference spectrum-however, has been complicated by the fact that electrons tunneling from the STS tip into the system can tunnel either into the heavy magnetic moment or the light conduction band states.

Robust upward dispersion of the neutron spin resonance in the heavy fermion superconductor CeYbCoIn.

The neutron spin resonance is a collective magnetic excitation that appears in the unconventional copper oxide, iron pnictide and heavy fermion superconductors. Although the resonance is commonly associated with a spin-exciton due to the d(s)-wave symmetry of the superconducting order parameter, it has also been proposed to be a magnon-like excitation appearing in the superconducting state. Here we use inelastic neutron scattering to demonstrate that the resonance in the heavy fermion superconductor CeYbCoIn with x=0, 0.

Evaluation of a Gadolinium-Based Nanoparticle (AGuIX) for Contrast-Enhanced MRI of the Liver in a Rat Model of Hepatic Colorectal Cancer Metastases at 9.4 Tesla.

Purpose: The aim of this study was to compare a Gd-based nanoparticle (AGuIX) with a standard extracellular Gd-based contrast agent (Gd-DOTA) for MRI at 9.4 T in rats with hepatic colorectal cancer metastases.

Materials And Methods: 12 rats with hepatic metastases were subjected to MRI using a 9.

Coherent transport and energy flow patterns in photosynthesis under incoherent excitation.

Long-lived coherences have been observed in photosynthetic complexes after laser excitation, inspiring new theories regarding the extreme quantum efficiency of photosynthetic energy transfer. Whether coherent (ballistic) transport occurs in nature and whether it improves photosynthetic efficiency remain topics of debate. Here, we use a nonequilibrium Green's function analysis to model exciton transport after excitation from an incoherent source (as opposed to coherent laser excitation).

Atomic resolution imaging of currents in nanoscopic quantum networks via scanning tunneling microscopy.

We propose a new method for atomic-scale imaging of spatial current patterns in nanoscopic quantum networks by using scanning tunneling microscopy (STM). By measuring the current flowing from the STM tip into one of the leads attached to the network as a function of tip position, one obtains an atomically resolved spatial image of "current riverbeds" whose spatial structure reflects the coherent flow of electrons out of equilibrium. We show that this method can be successfully applied in a variety of network topologies and is robust against dephasing effects.

Hybrid III anthropomorphic test device (ATD) response to head impacts and potential implications for athletic headgear testing.

The Hybrid III 50th percentile male anthropomorphic test device (ATD) is the most widely used human impact testing surrogate and has historically been used in automotive or military testing. More recently, this ATD is finding use in applications evaluating athletic helmet protectivity, quantifying head impact dosage and estimating injury risk. But ATD head-neck response has not been quantified in omnidirectional athletic-type head impacts absent axial preload.

Boxing and mixed martial arts: preliminary traumatic neuromechanical injury risk analyses from laboratory impact dosage data.

Object: In spite of ample literature pointing to rotational and combined impact dosage being key contributors to head and neck injury, boxing and mixed martial arts (MMA) padding is still designed to primarily reduce cranium linear acceleration. The objects of this study were to quantify preliminary linear and rotational head impact dosage for selected boxing and MMA padding in response to hook punches; compute theoretical skull, brain, and neck injury risk metrics; and statistically compare the protective effect of various glove and head padding conditions.

Methods: An instrumented Hybrid III 50th percentile anthropomorphic test device (ATD) was struck in 54 pendulum impacts replicating hook punches at low (27-29 J) and high (54-58 J) energy.

Defects in heavy-fermion materials: unveiling strong correlations in real space.

Defects provide important insight into the complex electronic and magnetic structure of heavy-fermion materials by inducing qualitatively different real-space perturbations in the electronic and magnetic correlations of the system. These perturbations possess direct experimental signatures in the local density of states, such as an impurity bound state, and the nonlocal spin susceptibility. Moreover, highly nonlinear quantum interference between defect-induced perturbations can drive the system through a first-order phase transition to a novel inhomogeneous ground state.

Theory of multiband superconductivity in spin-density-wave metals.

We study the emergence of multiband superconductivity with s- and d-wave symmetry on the background of a spin density wave (SDW). We show that the SDW coherence factors renormalize the momentum dependence of the superconducting (SC) gap, yielding a SC state with an unconventional s-wave symmetry. Interband Cooper pair scattering stabilizes superconductivity in both symmetries.

Differential conductance and quantum interference in Kondo systems.

We present a large-N theory for the differential conductance, dI/dV, in Kondo systems measured via scanning tunneling spectroscopy. We demonstrate that quantum interference between tunneling processes into the conduction band and into the magnetic f-electron states is crucial in determining the experimental Fano line shape of dI/dV. This allows one to uniquely extract the Kondo coupling and the ratio of the tunneling amplitudes from the experimental dI/dV curve.

Experimental evaluation of underride analysis techniques and empirical validation of a new analytical technique.

Accident reconstructionists are often faced with damage patterns and locations on vehicles that are not well defined by available barrier impact data. One such example is a frontal underride collision. Underride impacts occur when there is a height mismatch between the primary structural components of the impacting vehicles, and the vehicle with the lower height is forced beneath the structure of the other vehicle.

Minor crashes and 'whiplash' in the United States.

In the United States there is currently a paucity of available real world minor rear crash data with struck vehicle delta-V, or speed change, less than or equal to 15 kilometers per hour. These data are essential as researchers attempt to define 'whiplash' injury risk potential in these minor crashes. This study analyzed a new set of 105 U.

Magnetic resonance in the spin excitation spectrum of electron-doped cuprate superconductors.

We study the emergence of a magnetic resonance in the superconducting state of the electron-doped cuprate superconductors. We show that the recently observed resonance peak in the electron-doped superconductor Pr0.88LaCe0.