Competing ferromagnetism and superconductivity on FeAs layers in EuFe2(As0.73P0.27)2

We have measured the spin-polarized electron momentum density distributions of EuFe2(As0.73P0.27)2 by magnetic Compton scattering (MCS) measurements. For the first time, we show direct evidence of competing ferromagnetism and superconductivity (SC) on FeAs layers in this iron pnictide system. The MCS orbitalwise decomposition of the density distributions reveals that between 16 and 19 K, the spin-polarized Fe-3d character is enhanced (as the ferromagnetic character supersedes superconducting character), where the resistivity shows a maximum, reentrant SC-like peak, at 18 K. The spin polarization of the Fe-3d orbital, enhanced by ferromagnetic Eu ions, suppresses the SC around 18 K, while at other temperatures the system indeed exhibits SC where the Fe-3d spin polarization is suppressed or collapses.     

Shape-memorizable styrene-butadiene block copolymer. I. Thermal and mechanical behaviors and structural change with deformation

Thermal properties in the range from room temperature to 150°C, mechanical properties from room temperature to 80°C, and structural changes by drawing and contraction at 80°C followed by crystallization have been studied in a crystalline styrene-butadiene block copolymer, which has the property of shape memory, using differential scanning calorimetry (DSC), mechanical analysis, wide-angle x-ray diffraction (WAXD), and smallangle x-ray scattering (SAXS). This copolymer has the crystal transformation temperature, the melting temperature of the trans- 1,4-polybutadiene domains, and the higher glass transition temperature of the polystyrene domains. When a high strain is adopted for the deformation at 80°C (i.e., between the melting temperature of the polybutadiene [PB] domains and the glass transition temperature of the polystyrene regions) and crystallization conditions with fixed ends are employed, a fibrillar structure with a better regularity of long spacings and a high orientation of crystals forms. When the drawn sample is allowed to contract at 80°C, the high contraction or the shape recovery appears. Nevertheless, crystallization after contraction presents essentially the same supermolecular structure as that before contraction. It is suggested that the molecular chains of polybutadiene were inhibited from flowing freely by the glassy polystyrene molecules and that there must be some structural units separated by amorphous domains that contribute to the elongation and contraction at the high temperature.     

The N = 16 Spherical Shell Closure in 24O

The unbound excited states of the most neutron-rich dripline oxygen isotope, ²⁴O, have been investigated by using the ²⁴O(p,p′)²⁴O^* reaction at the beam energy of 62 MeV/nucleon in inverse kinematics. The first and second unbound excited states of ²⁴O have been observed at ${E_{\rm x}= 4.63_{-0.14}^{+0.30}}$  MeV and ${E_{\rm x}= 5.13_{-0.24}^{+0.19}}$  MeV (preliminary) along with the evidence for another higher lying state at around 7.3 MeV. The quadrupole deformation parameter ${\beta_{2^+}}$ was deduced to be ${0.15_{-0.03}^{+0.08}}$ (preliminary) for the first time. The systematics of the ${\beta_{2^+}}$ and the ${E_{\rm x}(2_1^+)}$ in the Z = 8 isotopes shows the N = 16 spherical shell closure in ²⁴O.     

Palladium‐Catalyzed Construction of Quaternary Stereocenters by Enantioselective Arylation of γ‐Lactams with Aryl Chlorides and Bromides

Herein, we report the first Pd‐catalyzed enantioselective arylation of α‐substituted γ‐lactams. Two sets of conditions were developed for this transformation, allowing for the use of either aryl chlorides or bromides as electrophiles. Utilizing a highly electron‐rich dialkylphosphine ligand we have been able to construct α‐quaternary centers in good yields (up to 91 % yield) and high enantioselectivities (up to 97 % ee).     

Coexistence of covalent superdeformation and molecular resonances in an unbound region of 12Be

The generalized two-center cluster model, which can treat static structures and dynamical reactions in excited states, is applied to the light neutron-rich system, 12Be=alpha+alpha+4N. We discuss the change of the neutrons' configuration around two alpha cores from the covalent structure to the ionic one. We show that, in the unbound region above particle-decay thresholds, the ionic configurations appear as the molecular resonances of alpha+8He, 6He+6He, and 5He+7He. A new type of superdeformation is possible, and we find here a covalent superdeformation with a hybrid configuration of both the covalent and ionic structures. The excitation of these exotic structures through the two-neutron transfer reaction is also discussed.     

Interaction of highly charged ions with carbon-based materials using Kobe EBIS

Interaction of highly charged ions (HCIs) with surfaces produce various specific phenomena as a consequence of the potential energy that HCI possesses. In the present study, we have observed photon emission, structural, magnetic, and electronic modification on various carbon-based materials such as carbon nanotube by the impact of HCIs using an electron beam ion source named Kobe EBIS installed at the Kobe University. In order to study the potential effect, HCIs of Ar^q+ (q = 6–16) with the intensity of 0.1–1 nA are projected on the surface with a constant kinetic energy (16 keV). For photon emission measurements, we observed spatial and spectral distribution of visible light emission from the surface during irradiation with HCIs. On the other hand, the structural modification of multi-walled carbon nanotubes (MWCNTs) irradiated with HCIs has been analyzed using a transmission electron microscopy and Raman spectroscopy. Irradiation effects on the resistivity of single MWCNT supported on micrometer scale bridge pattern were also measured. We have also measured magnetic structure of highly oriented pyrolytic graphite irradiated with HCIs using electron spin resonance at low temperature. At the present paper, we will review our recent experimental results on the interaction of HCI with various carbon-based materials.