Related papers: Pair excitations of a quantum spin on a proximitiz…
The nature of the attractive electron-electron interaction, leading to the formation of Cooper-pairs in unconventional superconductors has still to be fully understood and is subject to intensive research. Here we show that the sequence…
The possible existence of a sign-changing gap symmetry in BaFe$_{2}$As$_{2}$-derived superconductors (SC) has been an exciting topic of research in the last few years. To further investigate this subject we combine Electron Spin Resonance…
We theoretically explore possible unconventional superconductivity induced by weak repulsive interactions in twisted bilayer TMD (e.g. WSe$_2$) in the presence of an out-of-plane electric field. Using renormalization group (RG) analysis, we…
We study theoretically spin excitations in the newly discovered nickelate superconductors based on a single-band model and the random phase approximation. The spin excitations are found to be incommensurate in a low energy region. A spin…
A theory of tunneling conductance in ferromagnetic metal/insulator/triplet - supercondcutor junctions is presented for unitary and non-unitary spin triplet pairing states which are promising candidates for the superconducting paring…
In the copper-oxide parent compounds of the high-transition-temperature superconductors, the valence electrons are localized, one per copper site, due to strong intraatomic Coulomb repulsion. A symptom of the localization is…
Pairing correlation of Cooper pair is a fundamental property of multi-fermion interacting systems. For nucleons, two modes of the Cooper-pair coupling may exist, namely of $S_{12}=0$ with $L_{12}=0$ (spin-singlet s-wave) and $S_{12}=1$ with…
Recent experiments reported the puzzling zero energy modes associated with ferromagnetic impurities in some iron-based superconductors with topological band structures. Here, we show that the sufficiently strong exchange coupling between a…
We present first-principles calculations of the coupling of quasiparticles to spin fluctuations in iron selenide and discuss which types of superconducting instabilities this coupling gives rise to. We find that strong antiferromagnetic…
The common tunneling picture of electron-positron pair creation in a strong electric field is generalized to pair creation in combined crossed electric and magnetic fields. This enhanced picture, being symmetric for electrons and positrons,…
Superconductivity, a state in which electrical currents can flow without resistance, occurs because of pairing of electrons into quasiparticles with integer spin $S$. In practically all known superconducting materials, these pairs form a…
We investigate theoretically the interplay of proximity effects due to the presence of a superconductor and normal ferromagnetic leads on the formation of the spintronic quadrupolar exchange field in a large-spin molecule. We show that the…
Through a non-perturbative quantum theory, we investigate how the quasi-electron excitations of a two-dimensional electron gas are modified by strong coupling to the vacuum field of a microcavity. We show that the electronic dressed states…
In cuprate superconductors, superconductivity is consistently accompanied by antiferromagnetism. This raises the question of a potential causal link between superconductivity and antiferromagnetic mechanisms. In this study, we consider the…
We investigate the behavior of magnetic impurities placed on the surface of superconductor thin films with spin-orbit coupling. Our study reveals long-range interactions between the impurities, which decay according to a power law, mediated…
Magnetic fluctuations is the leading candidate for pairing in cuprate, iron-based and heavy fermion superconductors. This view is challenged by the recent discovery of nodeless superconductivity in CeCu$_2$Si$_2$, and calls for a detailed…
High spin systems, like those that incorporate rare-earth $4f$ elements (REEs), are increasingly relevant in many fields. Although research in such systems is sparse, the large Hilbert spaces they occupy are promising for many applications.…
In strongly correlated materials, cooperative behavior of the electrons causes a variety of quantum ordered states that may, in some cases, coexist. It has long been believed, however, that such coexistence among ferromagnetic ordering,…
We demonstrate the existence of a new type of spatially localized excitations in the unitary Fermi gas: spin polarized droplets with a peculiar internal structure involving the abrupt change of the pairing phase at the surface of the…
We present a theory of the low-energy excitations of a ferromagnetic metal nanoparticle. In addition to the particle-hole excitations, which occur in a paramagnetic metal nanoparticle, we predict a branch of excitations involving the…