Related papers: Leading superconducting instabilities in three-dim…
The unconventional superconductivity in Sr$_2$RuO$_4$ continues to defy a unified interpretation. In this paper, we focus on some novel aspects of its superconducting pairing by exploiting the orbital degree of freedom in this material. The…
Ru based perovskites demonstrate an amazing richness in their magnetic properties, including 3D and quasi-2D ferromagnetism, antiferromagnetism, and unconventional superconductivity. Tendency to ferromagnetism, stemming from the unusually…
After more than 25 years of research, three even-parity superconducting states -- the $d+id$-wave, $d+ig$-wave, and $s+id$-wave states -- have emerged as leading candidates for the superconducting states of Sr$_2$RuO$_4$. In the present…
The putative spin-triplet superconductor UTe2 exhibits multiple superconducting phases under applied pressure [D. Braithwaite et al., Commun. Phys. 2, 147 (2019)]. The clarification of pairing mechanisms and symmetries of gap functions are…
In $\rm Sr_2RuO_4$ the spin excitation spectrum is dominated by incommensurate fluctuations at q=(0.3 0.3 q$_z$), which arise from Fermi-surface nesting. We show that upon Ti substitution, known to suppress superconductivity, a short range…
The unique Fermi surfaces and their nesting properties of Sr2RuO4 are considered. The existence of unconventional superconductivity is shown microscopically, for the first time, from the magnetic interactions (due to nesting) and the…
The fluctuation conductivity $\sigma_{\rm s}$ in bulk superconductors with non s-wave pairing and with nonmagnetic disorder of strength $D$ is studied at low $T$ and within the Gaussian approximation. It is shown by assuming a quasi…
We investigate the superconductivity in Sr$_2$RuO$_4$ on the basis of the three-dimensional three-band Hubbard model. We propose a model with Coulomb interactions among the electrons on the nearest-neighbor Ru sites. In our model the…
We propose orbital fluctuations in a multi-band ground state as the superconducting pairing mechanism in the new iron-based materials. We develop a general SU(4) theoretical framework for studying a two-orbital model and discuss a number of…
The odd-parity spin-triplet Cooper pairing states show a six-fold degeneracy for a quasi-two-dimensional electron system. In this article we show how spin-orbit coupling can lift this degeneracy for Sr_2RuO_4 taking the band structure based…
In materials without an inversion center of symmetry the spin degeneracy of the conducting band is lifted by an antisymmetric spin orbit coupling (ASOC). Under such circumstances, spin and parity cannot be separately used to classify the…
Motivated by the recent finding of superconductivity in layered CoO_2 compounds, we investigate superconducting and magnetic instabilities of interacting electrons on the two-dimensional triangular lattice. Using a one-loop renormalization…
UTe2 is a promising candidate for spin-triplet superconductors, in which a paramagnetic normal state becomes superconducting due to spin fluctuations. The subsequent discovery of various unusual superconducting properties has promoted the…
Recent experiments make it appear more likely that the order parameter of the unconventional superconductor Sr$_2$RuO$_4$ has a spin-triplet $f$-wave symmetry. We study ultrasonic absorption and thermal conductivity of superconducting…
The pairing symmetry in the electron mechanism for superconductivity is explored when charge fluctuations coexist with spin fluctuations. The extended Hubbard model is adopted to obtain, with the fluctuation exchange approximation, a phase…
Quasi-one-dimensional electron systems display intrinsic instability towards long-range ordered phases at sufficiently low temperatures. The superconducting orders are of particular interest as they can possess either singlet or triplet…
We consider the SU(2) gauge theory for spin fluctuations in the two-dimensional Hubbard model, where the electron field is fractionalized in terms of spinons and chargons. In this theory, spinons are described by a non-linear sigma model,…
We study unconventional superconductivity in a two-dimensional locally noncentrosymmetric triangular lattice. The model is relevant to bilayer transition metal dichalcogenides with 2H$_b$ stacking structure, for example. The superconducting…
Even-parity interorbital spin-triplet pairing emerges as an intriguing candidate in multiorbital superconductors with significant Hund's and spin-orbit coupling. Within such a state, the pairing is dominated by the intraband…
Hund's pairing refers to Cooper pairing generated by onsite interactions that become attractive due to large Hund's exchange $J$. This is possible in multiorbital systems even when all local bare interactions are repulsive, since attraction…