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A superconducting KBi2 sample was successfully prepared using a liquid ammonia (NH3) technique. The temperature dependence of the magnetic susceptibility (M/H) showed a superconducting transition temperature (Tc) as high as 3.6 K. In addition, the shielding fraction at 2.0 K was evaluated to be 87%, i.e., a bulk superconductor was realized using the above method. The Tc value was the same as that reported for the KBi2 sample prepared using a high-temperature annealing method. An X-ray diffraction pattern measured based on the synchrotron X-ray radiation was analyzed using the Rietveld method, with a lattice constant, a, of 9.5010(1) A under the space group of Fd[3 with combining macron]m (face-centered cubic, no. 227). The lattice constant and space group found for the KBi2 sample using a liquid NH3 technique were the same as those reported for KBi2 through a high-temperature annealing method. Thus, the superconducting behavior and crystal structure of the KBi2 sample obtained in this study are almost the same as those for the KBi2 sample reported previously. Strictly speaking, the magnetic behavior of the superconductivity was different from that of a KBi2 sample reported previously, i.e., the KBi2 sample prepared using a liquid NH3 technique was a type-II like superconductor, contrary to that prepared using a high-temperature annealing method, the reason for which is fully discussed. These results indicate that the liquid NH3 technique is effective and simple for the preparation of a superconducting KBi2. In addition, the topological nature of the superconductivity for KBi2 was not confirmed.

Two-dimensional (2D) hybrid perovskites with novel functionalities and structural diversity are a perfect platform for emerging optoelectronic devices such as photodetectors, light-emitting diodes, and solar cells. Here, we demonstrate that excess concentration of Cesium bromide (CsBr) is key to the formation of easily exfoliated 2D Cs

We have investigated the low-temperature magnetism of sodium superoxide (NaO2), in which spin, orbital, and lattice degrees of freedom are closely entangled. The magnetic susceptibility shows anomalies at T1 = 220 K and T2 = 190 K, which correspond well to the structural phase transition temperatures, and a sudden decrease below T3 = 34 K. At 4.2 K, the magnetization shows a clear stepwise anomaly around 30 T with a large hysteresis. In addition, the muon spin relaxation experiments indicate no magnetic phase transition down to T = 0.3 K. The inelastic neutron scattering spectrum exhibits magnetic excitation with a finite energy gap. These results confirm that the ground state of NaO2 is a spin-singlet state. To understand this ground state in NaO2, we performed Raman scattering experiments. All the Raman-active libration modes expected for the marcasite phase below T2 are observed. Furthermore, we find that several new peaks appear below T3. This directly evidences the low crystal symmetry, namely, the presence of the phase transition at T3.We conclude that the singlet ground state of NaO2 is due to the spin-Peierls instability.

Polycrystalline rubidium superoxide (RbO2) has been synthesized by using solution method followed by the reaction process under the cooling condition of-40 °C. X-ray Powder Diffraction (XRD) spectra showed that RbO2 was successfully synthesized by this method. The magnetic susceptibility and pulsed muon spin relaxation (μSR) measurements were carried out in order to study the magnetic properties of RbO2.

Recently, ammonia-thermal reaction has been used for molecular intercalation in layered FeSe, resulting a new Lix(NH3)yFe2Se2 superconductor with Tc ~ 45 K. Here, we have used temperature dependent extended x-ray absorption fine structure (EXAFS) to investigate local atomic displacements in single crystals of this new superconductor. Using polarized EXAFS at Fe K-edge we have obtained direct information on the local Fe-Se and Fe-Fe bondlengths and corresponding mean square relative displacements (MSRD). We find that the Se-height in the intercalated system is lower than the one in the binary FeSe, suggesting compressed FeSe4 tetrahedron in the title system. Incidentally, there is hardly any effect of the intercalation on the bondlengths characteristics, revealed by the Einstein temperatures, that are similar to those found in the binary FeSe. Therefore, the molecular intercalation induces an effective compression and decouples the FeSe slabs. Furthermore, the results reveal an anomalous change in the atomic correlations across Tc, appearing as a clear decrease in the MSRD, indicating hardening of the local lattice mode. Similar response of the local lattice has been found in other families of superconductors, e.g., A15-type and cuprates superconductors. This observation suggests that local atomic correlations should have some direct correlation with the superconductivity.

A superconducting KBi

We performed X-ray diffraction (XRD) and DC magnetic susceptibility measurements to elucidate the crystal structure and superconducting properties of KSr2Nb3O10. From the diffraction pattern indexing, it was found that KSr2Nb3O10 crystallizes with monoclinic symmetry, space group P21/m(11). We succeeded in preparing high temperature (HT) and low temperature (LT) phases of KSr2Nb3O10 powder samples synthesized by a conventional solid state reaction and an ion-exchange reaction, respectively. Superconductivity was observed at 4 K by Li intercalation and it was found that the superconducting volume fraction of the LT phase (~ 1.4%) is clearly larger than that of the HT phase (0.07%).

18 O-labeled water (Water-18 O) is a widely used starting material of 18 F-labeled diagnostic agents in positron emission tomography (PET). Conventionally, Water-18 O has been separated from other stable oxygen isotope species (16 O, 17 O) by water distillation or nitric oxide distillation. However, conventional methods are costly and may have safety issues. In 2004, we developed the first unit of our novel oxygen isotope separation process by cryogenic oxygen distillation to overcome these issues. To meet the needs of the market, we built a second unit in 2013 and a third in 2016. We are now operating three commercially viable separation units with a total capacity of 600 kg of Water-18 O per year.

Topological superconductors have attracted wide-spreading interests for the bright application perspectives to quantum computing. Cu$_{0.3}$Bi$_2$Se$_3$ is a rare bulk topological superconductor with an odd-parity wave function, but the details of the vector order parameter $\textbf{{d}}$ and its pinning mechanism are still unclear. We have succeeded in growing Cu$_x$Bi$_2$Se$_3$ single crystals with unprecedented high doping levels. For samples with $x$ = 0.28, 0.36 and 0.37 with similar carrier density as evidenced by Knight shift, the in-plane upper critical field $H_{\rm c2}$ shows a two-fold symmetry. However, the angle at which the $H_{\rm c2}$ becomes minimal is different by 90$^\circ$ among them, which indicates that the $\textbf{{d}}$-vector direction is different for each crystal likely due to a different local environment. The carrier density for $x$ = 0.46 and 0.54 increases substantially compared to $x\leq$ 0.37. Surprisingly, the in-plane $H_{\rm c2}$ anisotropy disappears, indicating that the gap symmetry undergoes a transition from nematic to isotropic (possibly chiral) as carrier increases., Comment: Nat. Commun. (in press)

Magnetic pulse welding (MPW) which is one of the impact welding methods is suitable for a wide variety of combinations of similar and dissimilar metals. The flyer plate is accelerated by electromagnetic force and collided to the parent plate. A characteristic wavy interface is formed. The impact velocity and impact angle of the flyer plate during impact are important parameters which affect the interface morphology. In the case of dissimilar metals (e.g. Al/Cu, Al/Fe), the intermediate layer (such as intermetallic compound (IMC)) is formed by wavy interface formation and local temperature increase. The intermediate layer often decreases the bonding strength. Wavy interface formation mechanism and temperature increase at the joint interface should be investigated in order to obtain the dissimilar metal joint with high bonding strength. In this study, the impact velocity and impact angle of the flyer plate were obtained by using ANSYS Emag-Mechanical. Based on the obtained impact velocity and impact angle of the flyer plate in the MPW, the wavy interface formation and temperature change were reproduced by using ANSYS Autodyn for solving non-liner dynamics problems. Al sheets and Cu sheets were joined by the MPW. The joint interface was observed by OM and SEM and compared to the simulation result.

We report here the superconducting properties of a Laves phase superconductor SrIr2, which has a cubic MgCu2 structure. SrIr2 is a type-II superconductor, with a T c of 5.9 K. The estimated superconducting parameters of lower critical field µ 0 H c1 and upper critical field µ 0 H c2, coherence length ξ(0), penetration depth λ(0) and Ginzburg-Landau (GL) parameter κ(0) are approximately µ 0 H c1 = 101 Oe, µ 0 H c2(0) = 5.9 T, ξ(0) = 7.47 nm, λ(0) = 237 nm, and κ(0) = 31.7, respectively. The specific-heat data indicate that SrIr2 is a strong-coupling superconductor because the value of ΔC/γT c is approximately 1.71, which is larger than the value of 1.43 that is expected from the BCS theory. The physical properties obtained in this study are explained well by theoretical calculations including spin-orbit coupling (SOC). This result indicates that the physical properties of SrIr2 are strongly affected by the presence of SOC.

Alkali superoxide CsO2 is one of candidates for the spin-1/2 one-dimensional (1D) antiferromagnet, which may be sequentially caused by an ordering of the pi-orbital of O2- molecule below TS ~ 70 K. Here, we report on the magnetism in powder CsO2 and high-magnetic field magnetization measurements in pulsed-magnetic fields of up to 60 T. We obtained the low temperature phase diagram around the antiferromagnetic ordering temperature TN = 9.6 K under the magnetic field. At 1.3 K, remarkable up-turn curvature in the magnetization around a saturation field of ~ 60 T is found, which corresponds to the spin-1/2. We will compare it with the theoretical calculation., Comment: 11 pages, 3 figures

‘Aromatic hydrocarbon’ implies an organic molecule that satisfies the (4 n + 2) π-electron rule and consists of benzene rings. Doping solid aromatic hydrocarbons with metals provides the superconductivity. The first discovery of such superconductivity was made for K-doped picene (K x picene, five benzene rings). Its superconducting transition temperatures ( T c ’s) were 7 and 18 K. Recently, we found a new superconducting K x picene phase with a T c as high as 14 K, so we now know that K x picene possesses multiple superconducting phases. Besides K x picene, we discovered new superconductors such as Rb x picene and Ca x picene. A most serious problem is that the shielding fraction is ⩽15% for K x picene and Rb x picene, and it is often ∼1% for other superconductors. Such low shielding fractions have made it difficult to determine the crystal structures of superconducting phases. Nevertheless, many research groups have expended a great deal of effort to make high quality hydrocarbon superconductors in the five years since the discovery of hydrocarbon superconductivity. At the present stage, superconductivity is observed in certain metal-doped aromatic hydrocarbons (picene, phenanthrene and dibenzopentacene), but the shielding fraction remains stubbornly low. The highest priority research area is to prepare aromatic superconductors with a high superconducting volume-fraction. Despite these difficulties, aromatic superconductivity is still a core research target and presents interesting and potentially breakthrough challenges, such as the positive pressure dependence of T c that is clearly observed in some phases of aromatic hydrocarbon superconductors, suggesting behavior not explained by the standard BCS picture of superconductivity. In this article, we describe the present status of this research field, and discuss its future prospects.

Highlight qEMF3, a novel QTL for the early-morning flowering trait to mitigate heat-induced spikelet sterility at flowering in rice, was identified using a wild rice, Oryza officinalis, as a genetic resource., A decline in rice (Oryza sativa L.) production caused by heat stress is one of the biggest concerns resulting from future climate change. Rice spikelets are most susceptible to heat stress at flowering. The early-morning flowering (EMF) trait mitigates heat-induced spikelet sterility at the flowering stage by escaping heat stress during the daytime. We attempted to develop near-isogenic lines (NILs) for EMF in the indica-type genetic background by exploiting the EMF locus from wild rice, O. officinalis (CC genome). A stable quantitative trait locus (QTL) for flower opening time (FOT) was detected on chromosome 3. A QTL was designated as qEMF3 and it shifted FOT by 1.5–2.0h earlier for cv. Nanjing 11 in temperate Japan and cv. IR64 in the Philippine tropics. NILs for EMF mitigated heat-induced spikelet sterility under elevated temperature conditions completing flower opening before reaching 35°C, a general threshold value leading to spikelet sterility. Quantification of FOT of cultivars popular in the tropics and subtropics did not reveal the EMF trait in any of the cultivars tested, suggesting that qEMF3 has the potential to advance FOT of currently popular cultivars to escape heat stress at flowering under future hotter climates. This is the first report to examine rice with the EMF trait through marker-assisted breeding using wild rice as a genetic resource.

We fabricated picene thin-film field-effect transistors (FETs) with an ionic liquid gel and ionic liquid sheet as the gate electrolyte, and then used electron spin resonance (ESR) to investigate the carrier injection process in the organic electric double layer (EDL) FET. The ESR spectra strongly depended on the morphology of gate electrolytes. Three types of carrier injection processes in the EDL-FET were observed by examining the applied-bias time, organic-layer thickness, and gate-voltage dependencies of the electric-field-induced ESR spectrum: (1) interface injection due to electrostatic EDL formation, (2) bulk injection due to penetration of ions (electrochemical bulk doping), and (3) electrochemical reaction. These findings are significant for designing novel materials using the EDL-FET technique because three different carrier injection processes may lead to different physical properties, even in the same organic material.

The characteristics of field-effect transistors (FETs) fabricated from thin films and single crystals of phenacene molecules are fully reported in this review together with the electronic and crystal structures of phenacenes. Phenacene molecules possess a low HOMO level and a wide band gap. The highest mobility observed in the phenacene thin-film FETs is 7.4 cm2 V–1 s–1 for [6]phenacene, and in single-crystal FETs the highest value is 6.3 cm2 V–1 s–1 for [7]phenacene. The phenacene thin-film FETs show O2-sensing properties unlike their single-crystal FETs. The bias-stress effect is fully investigated for phenacene single-crystal FETs. Furthermore, the low-voltage operation of phenacene single-crystal FETs with electric-double-layer (EDL) capacitors is reported. The temperature dependence of phenacene single-crystal FETs is reported to clarify the transport mechanism, which is suggestive of band-like transport.

Summary Reconfigurable computing (RC) is a new paradigm that addresses the conflicting design requirements of high performance and high area density. Coarse-grained architecture RC (CGA-RC) operates at the word level of granularity and exhibits better power and performance features than fine-grained architectures. However, in a CGA-RC system, the processing elements (PE) implement several types of arithmetic operations and the routing between them has a fixed architecture. To achieve both good performance and high PE utilization for all applications, this paper proposes an interactive circuit design methodology for dynamically reconfigurable processors to accelerate their performance and achieve compact circuits. The method is applied to a JPEG encoder design and its performance evaluated.

X-ray powder diffraction (XRPD), magnetic susceptibility and muon-spin relaxation (μSR) measurements were carried out to investigate lattice symmetries and magnetic properties of one of alkali-meta...

We have investigated the magnetic properties of R 2 Fe 3 O 7 (R=Yb and Lu), which belongs to the homologous family of electronic ferroelectric RFe 2 O 4 . Magnetization measurements show ferrimagnetic ordering at the Neel temperature ( T N ) of ~270 K, which is slightly higher than that of RFe 2 O 4 ( T N ~230–250 K). Observation of spin glass and exchange bias shows a coexistence of ferromagnetic and antiferromagnetic interactions, similarly to RFe 2 O 4 . This situation gives rise to a complex magnetic change and a broad peak of magnetic entropy change. Some characteristics, such as refrigeration temperatures higher than in RFe 2 O 4 , seem to offer a possibility of this system to applications.

We report syntheses of new superconducting metal-doped MoSe2 materials (MxMoSe2). The superconducting MxMoSe2 samples were prepared using a liquid NH3 technique and can be represented as ‘(NH3)yMxMoSe2’. The Tcs of these materials were approximately 5.0 K, independent of x and the specific metal atom. X-ray diffraction patterns of (NH3)yNaxMoSe2 were recorded using polycrystalline powders. An increase in lattice constant c showed that the Na atom was intercalated between MoSe2 layers. The x-independence of c was observed in (NH3)yNaxMoSe2, indicating the formation of a stoichiometric compound in the entire x range, which is consistent with the x-independence of Tc. A metallic edge of the Fermi level was observed in the photoemission spectrum at 30 K, demonstrating its metallic character in the normal state. Doping of MoSe2 with Li and K also yielded superconductivity. Thus, MoSe2 is a promising material for designing new superconductors, as are other transition metal dichalcogenides.