A theory of Andreev conductance is formulated for junctions involving normal metals (N) and multiband superconductors (S) and applied to the case of superconductors with nodeless extended s(+/-)-wave order parameter symmetry, as possibly realized in the recently discovered ferropnictides. We find qualitative differences from tunneling into s-wave or d-wave superconductors that may help to ident...

The varying metallic antiferromagnetic correlations observed in iron-based superconductors are unified in a model consisting of both itinerant electrons and localized spins. The decisive factor is found to be the sensitive competition between the superexchange antiferromagnetism and the orbital-degenerate double-exchange ferromagnetism. Our results reveal the crucial role of Hund's rule couplin...

Since the announcement in 2011 of the Materials Genome Initiative by the Obama administration, much attention has been given to the subject of materials design to accelerate the discovery of new materials that could have technological implications. Although having its biggest impact for more applied materials like batteries, there is increasing interest in applying these ideas to predict new su...

We describe a new dual-polarized slot antenna to be used with quasi-optical devices such as superconductor-insulatorsuperconductor (SIS) mixers at millimeter and submillimeter wavelengths. The radiation and impedance characteristics of the antenna were obtained from a moment-method calculation. The antenna has an excellent radiation pattern, a low impedance, wide bandwidth, and low cross polari...

Iron chalcogenides, binary FeSe, FeTe and ternary FeTe x Se1-x , FeTe x S1-x and FeTe:O x , are the simplest compounds amongst the recently discovered iron-based superconductors. Thin films of iron chalcogenides present many attractive features that are covered in this review, such as: (i) easy fabrication and epitaxial growth on common single-crystal substrates; (ii) strong enhancement of supe...

A laser-based angle resolved photoemission (ARPES) system utilizing 6 eV photons from the fourth harmonic of a mode-locked Ti:sapphire oscillator is described. This light source greatly increases the momentum resolution and photoelectron count rate, while reducing extrinsic background and surface sensitivity relative to higher energy light sources. In this review, the optical system is describe...

We describe a new dual-polarized slot antenna to be used with quasi-optical devices such as superconductor-insulatorsuperconductor (SIS) mixers at millimeter and submillimeter wavelengths. The radiation and impedance characteristics of the antenna were obtained from a moment-method calculation. The antenna has an excellent radiation pattern, a low impedance, wide bandwidth, and low cross polari...

We introduce the concept of three-dimensional Dirac (Weyl) superconductors (SC), which have protected bulk fourfold (twofold) nodal points and surface Majorana arcs at zero energy. We provide a sufficient criterion for realizing them in centrosymmetric SCs with odd-parity pairing and mirror symmetry. Pairs of Dirac nodes appear in a mirror-invariant plane when the mirror winding number is nontr...

The compound Bi2Sr2CaCu208+6 is of special interest for two reasons: it is an important member of the family of cuprates who possess superconducting transitions at high temperatures, and it is an example of the class of layered compounds whose structures are distinguished by incommensurate modulation. The unique normal state and superconducting properties of the cuprates are intricately linked ...

The structure of a superconducting vortex has been studied theoretically for a dirty antiferromagnetic superconductor (AFSC), modelling an AFSC as a doped semi-metal with s-wave superconducting pairing and antiferromagnetic (dielectric) interaction between electrons (holes). It is also supposed that the quasiparticles dispersion law possesses the property of nesting. The distribution of the sup...