For the new high-temperature superconductor La${}_{3}$Ni${}_{2}$O${}_{7}$ under high pressure, authors analyze its pairing mechanism and symmetry in a bilayer two-orbital Hubbard model. By combining functional renormalization group weak-to-moderate interaction regime Gutzwiller approximation for low-energy effective model projected to atomic one- two-electron states strong-coupling regime, they find robust extended $s$-wave or ${s}_{\ifmmode\pm\else\textpm\fi{}}$-wave as triggered by spin...

In several recent experiments the superconducting gap of a single-unit-cell-thick FeSe film on SrTiO${}_{3}$ substrate has been observed by scanning tunneling spectroscopy and angle-resolved photoemission spectroscopy. The value is about nine times larger than that bulk under ambient pressure, suggesting much higher pairing energy scale ${T}_{c}$ all other iron-based superconductors thus calling for better understanding its mechanism. this paper we study effects screening due to...

The recent discovery of bulk superconductivity in trilayer nickelate La$_4$Ni$_3$O$_{10}$ with the critical temperature $T_c$ near $30$K under high pressure is attracting a new wave research interest, after breakthrough bilayer La$_3$Ni$_2$O$_7$ $80$K. similarities and differences electronic structure superconducting mechanism these two systems are urgent theoretical issues. In this Letter, we study band construct minimal tight-binding model for high-pressure phase terms nickel...

We nonperturbatively investigate the ground state magnetic properties of 2D half-filled SU($2N$) Hubbard model in square lattice by using projector determinant quantum Monte Carlo simulations combined with method local pinning fields. Long-range N\'eel orders are found for both SU(4) and SU(6) cases at small intermediate values $U$. In cases, long-range moments exhibit nonmonotonic behavior respect to $U$, which first grow then drop as $U$ increases. This result is fundamentally different...

The interplay between charge and spin degrees of freedom in strongly correlated fermionic systems, particular Dirac fermions, is a long-standing problem condensed matter physics. We investigate the competing orders half-filled $\mathrm{SU}(2N)$ Hubbard model on honeycomb lattice, which can be accurately realized optical lattices with ultracold large-spin alkaline-earth fermions. Employing large-scale projector determinant quantum Monte Carlo simulations, we have explored phase transitions...

We investigate the twisted bilayer graphene by a two-orbital Hubbard model on honeycomb lattice. The is studied near 1/4 band filling using singular-mode functional renormalization group theory. Spin-triplet $f$-wave pairing found from weak to moderate coupling limit of local interactions, and associated with Hund's rule incommensurate spin fluctuations at momenta.

Abstract Studying strong electron correlations has been an essential driving force for pushing the frontiers of condensed matter physics. In particular, in vicinity correlation-driven quantum phase transitions (QPTs), critical fluctuations multiple degrees freedom facilitate exotic many-body states and behaviours beyond Landau’s framework 1 . Recently, moiré heterostructures van der Waals materials have demonstrated as highly tunable platforms exploring fascinating, strongly correlated...

We study the electronic orders at lower van Hove filling in kagome lattice. In weak limit of Hubbard interaction $U$ versus hopping parameter $t$, we find that system develops itinerant ferromagnetism; intermediate range $U$, noncollinear magnetic order with orthogonal spin moments on nearest-neighbor bonds. This is fact a Chern insulator supporting quantized anomalous Hall conductance; strong limit, map model to $t$-$J$ $J = 4t^2/U$. For moderate values $J$ recover obtained model. However,...

The existence of degenerate or gapless edge states is a characteristic feature topological insulators, but difficult to detect in the presence interactions. We propose new method obtain degeneracy from perspective entanglement entropy, which very useful identify interacting states. Employing determinant quantum Monte Carlo technique, we investigate interaction effect on two representative models fermionic insulators one and dimensions, respectively. In topologically nontrivial phases,...

We design a novel formalism of determinant quantum Monte Carlo method for the half-filled Hubbard model with on-site interaction $U$ and nearest-neighbor density-density $V$ on square lattice. The is free sign problem $|U|\ensuremath{\ge}4|V|$, achieved by introducing discrete auxiliary fields bonds alone. Based this formalism, we study ground-state phase diagram systematically using projector algorithm. Within sign-problem parameter space obtain antiferromagnetism $U\ensuremath{\ge}4|V|>0$,...

The recent discovery of bulk superconductivity in trilayer nickelate ${\mathrm{La}}_{4}{\mathrm{Ni}}_{3}{\mathrm{O}}_{10}$ under high pressure is attracting a new wave research interest. In this Letter, we study its electronic band structure and construct minimal tight-binding model terms the nickel $3{d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ $3{d}_{3{z}^{2}\ensuremath{-}{r}^{2}}$ orbitals, investigate superconducting mechanism due to local Coulomb interactions by unbiased functional...

Optical switch based on an ultra-compact double-slot photonic crystal waveguide (DS-PCWG) with a titanium/aluminum microheater is demonstrated. The operating principle relies shifting transmission-dip caused by the defect mode coupling in band gap (PBG). Based unique PBG, low switching power of 9.2 mW and high extinction ratio 17 dB are achieved experimentally while length DS-PCWG only 16 μm.

There is a hot debate on the anomalous behavior of superfluid density ρ_{s} in overdoped La_{2-x}Sr_{x}CuO_{4} films recent years. The linear drop at low temperatures implies superconductors are clean, but scaling between (in zero temperature limit) and transition T_{c} hallmark dirty limit Bardeen-Cooper-Schrieffer (BCS) framework [I. Bozovic et al., Nature (London) 536, 309 (2016)NATUAS0028-083610.1038/nature19061]. This dichotomy motivated exotic theories beyond standard BCS theory. We...

Recently, the bulk nickelate La$_3$Ni$_2$O$_7$ is reported to show signature of high-temperature superconductivity under high pressure above $14$GPa [H. Sun et al., Nature 621, 493 (2023)]. We analyze pairing mechanism and symmetry in a bilayer Hubbard model with two orbitals $E_g$ multiplet. In weak moderate interaction regime, our functional renormalization group (FRG) calculations yield $S_\pm$-wave Cooper triggered by leading spin fluctuations. The gap function changes sign across Fermi...

Experimental signatures of Majorana zero modes in a single superconducting quantum wire with spin-orbit coupling have been reported as zero-bias peaks tunneling spectroscopy. We study whether these can persist an array coupled wires, and if not, what their remnant might be. The bulk exhibits topologically distinct gapped phases intervening gapless phase. Even though the pairing structure is topological, interaction between superfluid leads to spontaneous time-reversal symmetry breaking....

Abstract Purpose Treatment planning system (TPS) dose calculation is sensitive to multileaf collimator (MLC) modeling, especially when treating with intensity‐modulated radiation therapy (IMRT) or VMAT. This study investigates the dosimetric impact of MLC leaf‐tip model in a commercial TPS (RayStation v.6.1). The detectability modeling errors was assessed through both measurements an anthropomorphic head‐and‐neck phantom and patient‐specific IMRT QA using 3D diode array. Methods Materials An...

Motivated by recent scanning tunneling microscopy experiments on surfaces of ${\text{Bi}}_{1\ensuremath{-}x}{\text{Sb}}_{{x}^{\ensuremath{'}}}$ and ${\text{Bi}}_{2}{\text{Te}}_{3}$, we theoretically study the electronic structure a three-dimensional (3D) topological insulator in presence local impurity or domain wall its surface using 3D lattice model. While density states (LDOS) oscillates significantly space at energies above bulk gap, oscillation due to in-gap Dirac fermions is very weak....

We study the boundary Majorana modes for single component p-wave weak topological superconductors or superfluids, which form zero energy flat bands protected by time-reversal symmetry in orbital channel. However, due to divergence of density states, band flatness edge is unstable under spontaneously generated spatial variations Cooper pairing phases. Staggered current loops appear near and thus broken This effect can both condensed matter ultra-cold atom systems.

It is necessary to break both time-reversal and parity symmetries realize a Josephson, or superconducting, diode exhibiting nonreciprocal critical direct-currents (DC). In fact, these conditions are still insufficient. The dependencies of the free energy on phase difference across junction magnetic field classified, current-reversion (JR), field-reversion, field-current reversion conditions, respectively. To exhibit DC Josephson effect, all satisfying JR condition need be broken. relations...

We study the Hubbard model on square lattice coupled in addition to optical Su-Schrieffer-Heeger (SSH) phonons, using singular-mode functional renormalization group method. At half-filling and absence of interaction $U$, we find degenerate spin-density-wave (SDW)/charge-density-wave (CDW)/s-wave superconductivity (sSC) state at smaller electron-phonon coupling strength $\lambda$ higher phonon frequency $\omega$, valence bond solid (VBS) larger lower $\omega$. After switching a positive VBS...

We generalized the Gutzwiller projectional variational method for ground state of strongly correlated electron systems to case finite temperature. Under approximation, we show that this maps a temperature renormalized mean-field theory. As one key ingredients in theory, obtained an explicit expression projection entropy or change due projection. illustrate application theory Anderson impurity problem and half-filled Hubbard model compare more elaborate techniques. find qualitative agreement....