Related papers: Quasiparticle Scattering Interference in (K,Tl)Fex…
Many superconducting devices rely on the finite gap in the excitation spectrum of a superconductor: thanks to this gap, at temperatures much smaller than the critical one the number of excitations (quasiparticles) that can impact the…
Effects of the backward scattering with large momentum transfer are examined in two-dimensional electron system with a special emphasis on electrons around ($\pi$,0), (0,$\pi$). The phase diagram is shown in the plane of temperature $T$ and…
The Cooper pairing mechanism of heavy-fermion superconductors, while long hypothesized as due to spin fluctuations, has not been determined. It is the momentum space (k-space) structure of the superconducting energy gap delta(k) that…
A known source of decoherence in superconducting qubits is the presence of broken Cooper pairs, or quasiparticles. These can be generated by high-energy radiation, either present in the environment or purposefully introduced, as in the case…
We study quantum interference of electronic waves that are scattered by multiple non-magnetic impurities in a d_x2-y2-wave superconductor. We show that the number of resonance states in the density-of-states (DOS), as well as their…
We performed a high-resolution angle-resolved photoemission spectroscopy study of the Tl$_{0.63}$K$_{0.37}$Fe$_{1.78}$Se$_2$ superconductor ($T_c=29$ K). We show the existence of two electronlike bands at the M$(\pi, 0)$ point which cross…
In the ultra-thin regime, Bi2Te3 films feature two surfaces (with each surface being a two-dimensional Dirac-fermion system) with complicated spin textures and a tunneling term between them. We find in this regime that the quasiparticle…
The discovery of the Fe pnictide superconductors generated great interest as the structure consists of planes of a magnetic material quite similar to the cuprate superconductors. Fe(Te0.5Se0.5) is a particularly simple system whose planes…
Identifying, quantifying, and suppressing decoherence mechanisms in qubits are important steps towards the goal of engineering a quantum computer or simulator. Superconducting circuits offer flexibility in qubit design; however, their…
The electronic structure of the high-T_c superconductor Tl2Ba2CuO6+d is studied by ARPES. For a very overdoped Tc=30K sample, the Fermi surface consists of a single large hole pocket centered at (pi,pi) and is approaching a topological…
Motivated by the recent results on impurity effects in MgB2, we present a theoretical model for a two-band superconductor in which the character of quasiparticle motion is ballistic in one band and diffusive in the other. We apply our model…
The identification, control and theoretical modelling of spin-triplet superconductors (STC) remain a central theme in quantum materials research. Intrinsic STC are rare but offer rich condensate properties and unique surface properties…
Quasiparticle interference (QPI) imaging of Bogoliubov excitations in quasi-two dimensional unconventional superconductors has become a powerful technique for measuring the superconducting gap and its symmetry. Here, we present the…
Josephson weak links made of two-dimensional topological insulators (TIs) exhibit magnetic oscillations of the supercurrent that are reminiscent of those in superconducting quantum interference devices (SQUIDs). We propose a microscopic…
Coherence factors are a hallmark of superconductivity as a pair-condensation phenomenon. When electrons pair, quasi-particles develop an acute sensitivity to different types of scattering potential, described by the appearance of coherence…
The Fermi surface pockets that lie at the corner of the two-iron Brillouin zone in heavily electron-doped iron selenide superconductors are accounted for by an extended Hubbard model over the square lattice of iron atoms that includes the…
Understanding topological matter in the fractional quantum Hall (FQH) effect requires identifying the nature of edge state quasiparticles. FQH edge state at the filling factor $\nu=2/3$ in the spin-polarized and non-polarized phases is…
The spin resonance observed in the inelastic neutron scattering data on Fe-based superconductors has played a prominent role in the quest for determining the symmetry of the order parameter in these compounds. Most theoretical studies of…
Layered cobaltates embody novel realizations of correlated quantum matter on a spin-1/2 triangular lattice. We report a high-resolution systematic photoemission study of the insulating cobaltates (Na1/2CoO2 and K1/2CoO2). Observation of…
Cooper pairing in the iron-based high-Tc superconductors is often conjectured to involve bosonic fluctuations. Among the candidates are antiferromagnetic spin-fluctuations and d-orbital fluctuations amplified by phonons. Any such…