Superconductivity
Bogoliubov Fermi surfaces of superconducting states arise from point or line nodes by breaking time-reversal symmetry. Because line and point nodes often accompany topologically protected zero-energy surface Andreev bound states (ASBSs) and…
The discovery of high-$T_c$ superconductivity (SC) in La$_3$Ni$_2$O$_7$ (LNO) has aroused a great deal of interests. Previously, it was proposed that the Ni-$3d_{z^2}$ orbital is crucial to realize the high-$T_c$ SC in LNO: The preformed…
We present a theoretical prediction of a phonon-mediated two-gap superconductivity in infinite-layer nickelates Nd$_{0.8}$Sr$_{0.2}$NiO$_2$ by performing $\textit{ab initio}$ $GW$ and $GW$ perturbation theory calculations. Electron $GW$…
While spin-triplet pairing remains elusive in nature, there is a growing effort to realize proximity-induced equal-spin triplet superconductivity in junctions with magnetic regions or an applied magnetic field and common $s$-wave…
We report direct measurements of the magnetic field screening at the limits of the Meissner phase for two superconducting Nb samples. The samples are processed with two different surface treatments that have been developed for…
We investigated the Re-based kagome superconductor Re$_2$Zr through various measurements, including resistivity, magnetization, specific heat, and muon spin rotation and relaxation spectroscopy. These results suggest that Re$_2$Zr is a…
We theoretically investigate the temperature dependence of nuclear spin-lattice relaxation rate $T_1^{-1}$ in bulk odd-frequency superconductivity. For a model odd-frequency pairing interaction, we first evaluate the superconducting order…
Flat-band systems are of great interest due to their strong electron correlations and unique band geometry. Recent studies have linked the properties of Cooper pairs in flat-band superconductors to the quantum metric. Unlike prior studies…
High-temperature high-pressure superconducting hydrides are typically characterized by cage-like hydrogenic lattices filled with electropositive metal atoms. Here, density functional theory based evolutionary crystal structure searches find…
We propose altermagnet-superconductor junctions as a way to achieve a thermoelectric response in metals free of external or stray magnetic fields. We combine qualitative analysis in a simplified model with a more rigorous approach based on…
We investigate the possible superconducting instabilities of strongly correlated electron materials using a generalization of linear response theory to external pairing fields depending on frequency. We compute a pairing susceptibility…
When the electron-phonon coupling is quadratic in the phonon coordinates, electrons can pair to form bipolarons due to phonon zero-point fluctuations, a purely quantum effect. We study superconductivity originating from this pairing…
Various clathrate superhydride superconductors have been found to possess hydrogen deficiency in experimental samples, while their impacts on superconductivity are often neglected. In this study, we investigate the superconductivity of…
We extend the scattering theory of the Josephson effect to include a coupling of the Josephson junction to a gapless electron reservoir in the normal state. By opening up the system with a quasiparticle escape rate $1/\tau$, the…
The kagome lattice is an intriguing and rich platform for discovering, tuning and understanding the diverse phases of quantum matter, which is a necessary premise for utilizing quantum materials in all areas of modern and future electronics…
The ability to efficiently control charge and spin in the cuprate high-temperature superconductors is crucial for fundamental research and underpins technological development. Here, we explore the tunability of magnetism, superconductivity…
Tunneling spectroscopy is an important tool for the study of both real-space and momentum-space electronic structure of correlated electron systems. However, such measurements often yield noisy data. Machine learning provides techniques to…
Traditional superconductors fall into two categories, type-I, expelling magnetic fields, and type-II, into which magnetic fields exceeding a lower critical field $H_{\rm c1}$ penetrate in form of Abrikosov vortices. Abrikosov vortices are…
After decades of research, superconductivity was finally found in nickel-based analogs of superconducting cuprates, with infinite-layer (IL) structure. These results are so far restricted to thin films in the case of IL-nickelates.…
We present a method for detecting the chirality $\chi$ of a ($d_{zx}+i \chi d_{yz}$)-wave superconductor through the analysis of the local density of states (LDOS) at the vortex core. Employing the quasiclassical Eilenberger theory, we…