Superconductivity up to 14.2 K in MnB Under Pressure.

The discovery of superconductivity in 3d transition-metal compounds with strong magnetism is interesting but rare. Especially for Mn-based compounds, there exist only very limited materials that show superconductivity. Here, the discovery of superconductivity is reported with an onset transition temperature up to 14.

Electronic correlations and partial gap in the bilayer nickelate LaNiO.

The discovery of superconductivity with a critical temperature of about 80 K in LaNiO single crystals under pressure has received enormous attention. LaNiO is not superconducting under ambient pressure but exhibits a transition at T  ≃ 115 K. Understanding the electronic correlations and charge dynamics is an important step towards the origin of superconductivity and other instabilities.

Record-High Superconducting Transition Temperature in a TiMn Alloy with the Rich Magnetic Element Mn.

It is well-known that magnetic moments are very harmful to superconductivity. A typical example is the element Mn, whose compounds usually exhibit strong magnetism. Thus, it is very difficult to achieve superconductivity in materials containing Mn.

Atomic scale disorder and reconstruction in bulk infinite-layer nickelates lacking superconductivity.

The recent discovery of superconductivity in infinite-layer nickelate films has sparked significant interest and expanded the realm of superconductors, in which the infinite-layer structure and proper chemical doping are both of the essence. Nonetheless, the reasons for the absence of superconductivity in bulk infinite-layer nickelates remain puzzling. Herein, we investigate atomic defects and electronic structures in bulk infinite-layer NdSrNiO using scanning transmission electron microscopy.

Enhancement of superconductivity and phase diagram of Ta-doped Kagome superconductor CsVSb.

Kagome superconductors AVSb (A = K, Rb, and Cs) have attracted enormous interest due to the coexistence of charge density wave (CDW) order, unconventional superconductivity (SC) and anomalous Hall effect (AHE). In this paper, we reported an intensive investigation on Cs(VTa)Sb single crystals with systematic Ta doping. Ta was confirmed to be doped into V-site in the Kagome layer from both single crystal X-ray diffraction structural refinement and scanning transmission electron microscopy observation.

Absence of near-ambient superconductivity in LuHN.

A recent study demonstrated near-ambient superconductivity in nitrogen-doped lutetium hydride. This stimulated a worldwide interest in exploring room-temperature superconductivity at low pressures. Here, by using a high-pressure and high-temperature synthesis technique, we have obtained nitrogen-doped lutetium hydride (LuHN), which has a dark-blue colour and a structure with the space group [Formula: see text] as evidenced by X-ray diffraction.

Visualizing the Atomic Configuration of Carbonate Groups in a (Cu,C)Ba Ca Cu O Superconductor.

Carbonates (CO ) have always been known as impurities to degrade the superconductivity in cuprate high-Tc superconductors. Herein, the atomic arrangement of carbonates is directly visualized in (Cu,C)Ba Ca Cu O via integrated differential phase contrast (iDPC) combined with state-of-the-art scanning transmission electron microscopy. The carbon atoms replace Cu atoms in the charge-reservoir layers, contributing to the formation of carbonates through strong orbital hybridization with the surrounding oxygen atoms.

Bamboo-like Vortex Chains Confined in Canals with Suppressed Superconductivity and Standing Waves of Quasiparticles.

The vortex core can be regarded as a nanoscale confined system for quasiparticles in a type-II superconductor. It is very interesting to investigate the interplay between the vortex core and other microscopic quantum confined systems. We observe band-like canals with the width of about 15 nm on the surface of KCa(FeNi)AsF ( = 0.

Comparative studies on superconductivity in CrRu compounds with bcc and A15 structures.

Chromium (Cr) is a transition metal element with 3orbital electrons. In most compounds containing Cr, due to the correlation effect, twofold features, namely localization and itinerancy are expected. The localization gives rise to a magnetic moment, while the latter exhibits as the effective coherent weight for conductivity.

Observation of anomalous amplitude modes in the kagome metal CsVSb.

The kagome lattice provides a fertile platform to explore novel symmetry-breaking states. Charge-density wave (CDW) instabilities have been recently discovered in a new kagome metal family, commonly considered to arise from Fermi-surface instabilities. Here we report the observation of Raman-active CDW amplitude modes in CsVSb, which are collective excitations typically thought to emerge out of frozen soft phonons, although phonon softening is elusive experimentally.

Superconductivity in nickel-based 112 systems.

Superconductivity has been discovered recently in infinite-layer nickel-based 112 thin films NiO ( = La, Nd, Pr and  = Sr, Ca). They are isostructural to the infinite-layer cuprate (Ca,Sr)CuO and are supposed to have a formal Ni 3 valence, thus providing a new platform to study the unconventional pairing mechanism of high-temperature superconductors. This important discovery immediately triggers a huge amount of innovative scientific curiosity in the field.

Direct visualization of a static incommensurate antiferromagnetic order in Fe-doped BiSrCaCuO.

In cuprate superconductors, due to strong electronic correlations, there are multiple intertwined orders which either coexist or compete with superconductivity. Among them, the antiferromagnetic (AF) order is the most prominent one. In the region where superconductivity sets in, the long-range AF order is destroyed.

Twofold symmetry of c-axis resistivity in topological kagome superconductor CsVSb with in-plane rotating magnetic field.

In transition metal compounds, due to the interplay of charge, spin, lattice and orbital degrees of freedom, many intertwined orders exist with close energies. One of the commonly observed states is the so-called nematic electron state, which breaks the in-plane rotational symmetry. This nematic state appears in cuprates, iron-based superconductor, etc.

Friedel Oscillations of Vortex Bound States under Extreme Quantum Limit in KCa_{2}Fe_{4}As_{4}F_{2}.

We report the observation of discrete bound states with the energy levels deviating from the widely believed ratio of 1∶3∶5 in the vortices of an iron-based superconductor KCa_{2}Fe_{4}As_{4}F_{2} through scanning tunneling microscopy (STM). Meanwhile Friedel oscillations of vortex bound states are also observed for the first time in related vortices. By doing self-consistent calculations of Bogoliubov-de Gennes equations, we find that at extreme quantum limit, the superconducting order parameter exhibits a Friedel-like oscillation, which modifies the energy levels of the vortex bound states and explains why it deviates from the ratio of 1∶3∶5.

Synthesis and physical properties of perovskite SmSrNiO(= 0, 0.2) and infinite-layer SmSrNiOnickelates.

Recently, superconductivity at about 9-15 K was discovered in NdSrNiO(Nd-112,≈ 0.125-0.25) infinite-layer thin films, which has stimulated enormous interests in related rare-earth nickelates.

Single particle tunneling spectrum of superconducting NdSrNiO thin films.

The pairing mechanism in cuprates remains as one of the most challenging issues in condensed matter physics. Recently, superconductivity was discovered in thin films of the infinite-layer nickelate NdSrNiO (x = 0.12-0.

Antiferromagnetism, charge ordering and stretched Ni-O bond in LnNiO (Ln = La, Nd).

Superconductivity was recently observed in Sr-doped NdNiO film after a long pursuit, which inspires us to investigate another Ruddlesden-Popper-based nickelate NdNiO which may hold an antiferromagnetic order and a charge stripe order. Through ab initio calculations, we find that the obtained results turn out to be similar to those of LaNiO. However, we propose that Ni ions in the charge stripe order observed in LaNiO are in fact antiferromagnetically coupled through a twofold double-exchange mediated by the intermediate Ni ion and the stretched Ni-O bond.

Decoupling of itinerant and localized d-orbital electrons in the compound ScZrCo.

By using the arc-melting method, we successfully synthesize the compound ScZrCo with the space group of-3. Both the resistivity and magnetic susceptibility measurements reveal a phase transition at about 86 K. This transition might be attributed to the establishment of an antiferromagnetic order.

Author Correction: Influence of microstructure on superconductivity in KFeSe and evidence for a new parent phase KFeSe.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Robust Zero Energy Modes on Superconducting Bismuth Islands Deposited on Fe(Te,Se).

Topological superconductivity is one of the frontier research directions in condensed matter physics. One of the unique elementary excitations in topological superconducting state is the Majorana Fermion (mode) which is its own antiparticle and obeys the non-Abelian statistics and is thus useful for constructing the fault-tolerant quantum computation. The evidence for Majorana Fermions (mode) in condensed matter is now quickly accumulated.

Directly visualizing the sign change of d-wave superconducting gap in BiSrCaCuO by phase-referenced quasiparticle interference.

The superconducting state is formed by the condensation of Cooper pairs and protected by the superconducting gap. The pairing interaction between the two electrons of a Cooper pair determines the gap function. Thus, it is pivotal to detect the gap structure for understanding the mechanism of superconductivity.

Comparative study of vortex dynamics in CaKFeAs and BaKFeAs single crystals.

We investigate the vortex dynamics in two typical hole doped iron based superconductors CaKFeAs (CaK1144) and BaKFeAs (BaK122) with similar superconducting transition temperatures. It is found that the magnetization hysteresis loop exhibits a clear second peak effect in BaK122 in wide temperature region while it is absent in CaK1144. However, a second peak effect of critical current density versus temperature is observed in CaK1144, which is however absent in BaK122.

Unprecedented high irreversibility line in the nontoxic cuprate superconductor (Cu,C)BaCaCuO.

One of the key factors that limit the high-power applications for a type II superconductor is the irreversibility line (), which reflects the very boundary of resistive dissipation in the phase diagram of magnetic field versus temperature. In cuprate family, the Y-, Bi-, Hg-, and Tl-based systems have superconducting transition temperatures exceeding the liquid nitrogen boiling temperature (~77 K). However, the toxic elements Hg and Tl in the latter two systems strongly constrain the applications.

Superconductivity with twofold symmetry in BiTe/FeTeSe heterostructures.

Topological superconductors are an interesting and frontier topic in condensed matter physics. In the superconducting state, an order parameter will be established with the basic or subsidiary symmetry of the crystalline lattice. In doped BiSe or BiTe with a basic threefold symmetry, it was predicted, however, that bulk superconductivity with order parameters of twofold symmetry may exist because of the presence of odd parity.

Discrete energy levels of Caroli-de Gennes-Matricon states in quantum limit in FeTeSe.

Caroli-de Gennes-Matricon (CdGM) states were predicted in 1964 as low-energy excitations within vortex cores of type-II superconductors. In the quantum limit, the energy levels of these states were predicted to be discrete with the basic levels at ±μΔ/E (μ = 1/2, 3/2, 5/2, …) with Δ the superconducting energy gap and E the Fermi energy. However, due to the small ratio of Δ/E in most type-II superconductors, it is very difficult to observe the discrete CdGM states, but rather a symmetric peak which appears at zero bias at the vortex center.