19 research outputs found
Triplet superconductivity from non-local Coulomb repulsion in Sn/Si(111)
Atomic layers deposited on semiconductor substrates introduce a platform for
the realization of the extended electronic Hubbard model, where the
consideration of electronic repulsion beyond the onsite term is paramount.
Recently, the onset of superconductivity at 4.7K has been reported in the
hole-doped triangular lattice of tin atoms on a silicon substrate. Through
renormalization group methods designed for weak and intermediate coupling, we
investigate the nature of the superconducting instability in hole-doped
Sn/Si(111). We find that the extended Hubbard nature of interactions is crucial
to yield triplet pairing, which is f-wave (p-wave) for moderate (higher) hole
doping. In light of persisting challenges to tailor triplet pairing in an
electronic material, our finding promises to pave unprecedented ways for
engineering unconventional triplet superconductivity.Comment: 4 pages, 3 figures (supplement: 3 pages, 2 figures
Van-Hove tuning of Fermi surface instabilities through compensated metallicity
Van-Hove (vH) singularities in the vicinity of the Fermi level facilitate the
emergence of electronically mediated Fermi surface instabilities. This is
because they provide a momentum-localized enhancement of density of states
enhancing selective electronic scattering channels. High-temperature
topological superconductivity has been argued for in graphene at vH filling
which, however, has so far proven inaccessible due to the demanded large doping
from pristine half filling. We propose compensated metallicity as a path to
unlock vH-driven pairing close to half filling in an electronic honeycomb
lattice model. It is enabled through the strong breaking of chiral symmetry
from intra-sublattice hybridization, leading to the emergence of a hole pocket
(hp) nearby the van-Hove points at the Brillouin zone boundary and an
electron pocket (ep) around the zone center . While the ep is radially
symmetric and barely contributing to the electronic ordering selection, the hp
is dominated by its vH signature and yields electronic order at elevated
scales.Comment: 4 pages, 2 figure
Robust -wave superconductivity of infinite-layer nickelates
Motivated by the recent observation of superconductivity in strontium doped
NdNiO, we study the superconducting instabilities in this system from
various vantage points. Starting with first-principles calculations, we
construct two distinct tight-binding models, a simpler single-orbital as well
as a three-orbital model, both of which capture the key low energy degrees of
freedom to varying degree of accuracy. We study superconductivity in both
models using the random phase approximation (RPA). We then analyze the problem
at stronger coupling, and study the dominant pairing instability in the
associated t-J model limit. In all instances, the dominant pairing tendency is
in the channel, analogous to the cuprate superconductors.Comment: 5 pages, 4 figures+ 5 pages, PRB Editors' suggestio
Van Hove tuning of AV3Sb5 kagome metals under pressure and strain
From first-principles calculations, we investigate the structural and electronic properties of the kagome metals AV3Sb5 (A=Cs, K, Rb) under isotropic and anisotropic pressure. Charge-ordering patterns are found to be unanimously suppressed, while there is a significant rearrangement of p-type and m-type Van Hove point energies with respect to the Fermi level. Already for moderate tensile strain along the V plane and compressive strain normal to the V layer, we find that a Van Hove point can be shifted to the Fermi energy. Such a mechanism provides an invaluable tuning knob to alter the correlation profile in the kagome metal, and suggests itself for further experimental investigation. It might allow us to reconcile possible multidome superconductivity in kagome metals not only from phonons but also from the viewpoint of unconventional pairing
Van Hove tuning of AV3Sb5 kagome metals under pressure and strain
From first-principles calculations, we investigate the structural and electronic properties of the kagome metals AV3Sb5 (A = Cs, K, Rb) under isotropic and anisotropic pressure. Charge-ordering patterns are found to be unanimously suppressed, while there is a significant rearrangement of p-type and m-type Van Hove point energies with respect to the Fermi level. Already for moderate tensile strain along the V plane and compressive strain normal to the V layer, we find that a Van Hove point can be shifted to the Fermi energy. Such a mechanism provides an invaluable tuning knob to alter the correlation profile in the kagome metal, and suggests itself for further experimental investigation. It might allow us to reconcile possible multidome superconductivity in kagome metals not only from phonons but also from the viewpoint of unconventional pairing
Van Hove tuning of AV3Sb5 kagome metals under pressure and strain
From first-principles calculations, we investigate the structural and electronic properties of the kagome metals AV3Sb5 (A=Cs, K, Rb) under isotropic and anisotropic pressure. Charge-ordering patterns are found to be unanimously suppressed, while there is a significant rearrangement of p-type and m-type Van Hove point energies with respect to the Fermi level. Already for moderate tensile strain along the V plane and compressive strain normal to the V layer, we find that a Van Hove point can be shifted to the Fermi energy. Such a mechanism provides an invaluable tuning knob to alter the correlation profile in the kagome metal, and suggests itself for further experimental investigation. It might allow us to reconcile possible multidome superconductivity in kagome metals not only from phonons but also from the viewpoint of unconventional pairing
Hybrid s-wave superconductivity in CrB
In a metal with multiple Fermi pockets, the formation of s-wave
superconductivity can be conventional due to electron-phonon coupling or
unconventional due to spin fluctuations. We analyze the hexagonal diboride
CrB, which is an itinerant antiferromagnet at ambient conditions and turns
superconducting upon increasing pressure. While the high pressure behavior of
T suggests conventional s-wave pairing, we find that spin fluctuations
promoting unconventional s-wave pairing become important in the vicinity of the
antiferromagnetic dome. As the symmetry class of the s-wave state is
independent of its underlying mechanism, we argue that CrB is a realization
of a hybrid s-wave superconductor where unconventional and conventional s-wave
mechanisms team up to form a joint superconducting dome
Rashba spin-orbit coupling in the square lattice Hubbard model: A truncated-unity functional renormalization group study
The Rashba-Hubbard model on the square lattice is the paradigmatic case for
studying the effect of spin-orbit coupling, which breaks spin and inversion
symmetry, in a correlated electron system. We employ a truncated-unity variant
of the functional renormalization group which allows us to analyze magnetic and
superconducting instabilities on equal footing. We derive phase diagrams
depending on the strengths of Rasbha spin-orbit coupling, real second-neighbor
hopping and electron filling. We find commensurate and incommensurate magnetic
phases which compete with d-wave superconductivity. Due to the breaking of
inversion symmetry, singlet and triplet components mix; we quantify the mixing
of d-wave singlet pairing with f-wave triplet pairing.Comment: 9 pages, 7 figure
Spatially modulated superconductivity in the Kagome Hubbard model
We identify a superconducting order featuring spatial pair modulations on the
kagome lattice subject to onsite Hubbard U and nearest neighbor V interactions.
Within our functional renormalization group analysis, this state appears with a
concomitant d-wave superconducting (SC) instability at zero lattice momentum,
where it distinguishes itself through intra-unit cell modulations of the
pairing function thus breaking the discrete space group symmetry. The relative
weight of the sublattice modulated superconductor (SMS) and d-wave SC is
influenced by the absolute interaction strength and coupling ratio V /U .
Parametrically adjacent to this domain at weak coupling, we find an intra-unit
cell modulated vestigial charge density wave and an s-wave SC instability. Our
study provides a microscopic setting and thorough description of this novel SMS
arising within a translation symmetry broken background