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The nuclear spin-lattice relaxation time T _1 of the ν = 2 quantum Hall ferromagnet (QHF) formed in a gate-controlled InSb two-dimensional electron gas has been characterized using a pump-probe technique. In contrast to a long T _1 of quantum Hall states around ν = 1 that possesses a Korringa-type temperature dependence, the temperature-independent short T _1 of the ν = 2 QHF suggests the presence of low energy collective spin excitations in a domain wall. Furthermore, T _1 of this ferromagnetic state is also found to be filling- and current-independent. The interpretation of these results as compared to the T _1 properties of other QHFs is discussed in terms of the domain wall skyrmion, which will lead to a better understanding of the QHF.

In GaAs quantum Hall (QH) systems, electrons are coupled with nuclear spins through the hyperfine interaction, which is normally not strong enough to change the dynamics of electrons and nuclear spins. The dynamics of the QH systems, however, may drastically change when the nuclear spins interact with low-energy collective excitation modes of the electron spins. We theoretically investigate the nuclear-electron spin interaction in the QH systems as hybrid quantum systems driven by the hyperfine interaction. In particular, we study the interaction between the nuclear spins and the Nambu–Goldstone (NG) mode with the linear dispersion relation associated with the U(1) spin rotational symmetry breaking. We show that such an interaction is described as nuclear spins collectively coupled to the NG mode, and can be effectively described by the Dicke model. Based on the model we suggest that various collective spin phenomena realized in quantum optical systems can also emerge in the QH systems.

A lipid transfer particle (LTP) from the hemolymph of adult male locusts, Locusta migratoria, was isolated and purified. The locust LTP exhibited its capacity to catalyze the exchange of diacylglycerol between low density lipophorin (LDLp) and high density lipophorin (HDLp). Contrary to the LTP reported for the tobacco hornworm, M. sexta, the locust LTP appeared to lack the capacity to promote net transfer of diacylglycerol to form an intermediate density lipophorin, although it seems premature to conclude the complete lack of such a capacity in locust LTP. The original concentration of LTP in hemolymph is assumed to be extremely low compared to that of lipophorin; only a catalytic amount of LTP may be present in the hemolymph (e.g., only 160 micrograms of LTP was obtained from the original hemolymph containing 400 mg protein). The molecular weight of intact LTP was estimated to be about 600,000 and the LTP was comprised of three glycosylated apoproteins, apoLTP-I (mol wt 310K), apoLTP-II (mol wt 89K), and apoLTP-III (mol wt 68K). The locust LTP contained significant amounts of lipids; the total lipid content amounted to 14.4% and the lipids were comprised of 17% hydrocarbons, 44% diacylglycerol, 8% cholesterol, 13% free fatty acid, and 18% phospholipids. The above molecular properties of locust LTP are essentially similar to those reported for M. sexta LTP.

The integer quantum Hall (QH) effects characterized by topologically quantized and nondissipative transport are caused by an electrically insulating incompressible phase that prevents backscattering between chiral metallic channels. We probed the incompressible area susceptible to the breakdown of topological protection using a scanning-gate technique incorporating nonequilibrium transport. The obtained pattern revealed the filling-factor- (ν-) dependent evolution of the microscopic incompressible structures located along the edge and in the bulk region. We found that these specific structures, respectively, attributed to the incompressible edge strip and bulk localization, show good agreement in terms of ν-dependent evolution with a calculation of the equilibrium QH incompressible phases, indicating the robustness of the QH incompressible phases under the nonequilibrium condition. Further, we found that the ν dependency of the incompressible patterns is, in turn, destroyed by a large imposed current during the deep QH effect breakdown. These results demonstrate the ability of our method to image the microscopic transport properties of a topological two-dimensional system.

The β decay of 75192Re117, which lies near the boundary between the regions of predicted prolate and oblate deformations, has been investigated using the KEK Isotope Separation System (KISS) in RIKEN Nishina Center. This is the first case in which a low-energy beam of rhenium isotope has been successfully extracted from an argon gas-stopping cell using a laser-ionization technique, following production via multi-nucleon transfer between heavy ions. The ground state of 192Re has been assigned Jπ=(0−) based on the observed β feedings and deduced logft values towards the 0+ and 2+ states in 192Os, which is known as a typical γ-soft nucleus. The shape transition from axial symmetry to axial asymmetry in the Re isotopes is discussed from the viewpoint of single-particle structure using the nuclear Skyrme-Hartree-Fock model.

We experimentally investigated the nitrogenation process of heavy rare earth (Gd, Tb, Dy, Ho and Er) hydrides dynamically by thermal analysis. The onset temperature of nitrogenation and the absolute value of nitrogenation enthalpy increased as the atomic number of the heavy rare earth elements increased and the onset temperature of nitrogenation with a sharp exothermic peak exhibited a large gap between Tb (406 °C) and Dy (806 °C). The reaction route R→RHx→RN has been done at a relatively low temperature and atmospheric pressure, indicating that the diffusion coefficient of nitrogen into the rare earth hydride is much higher than that of nitrogen into the rare earth metal and/or the activation energy of RHx→RN is lower than that of R→RN. For complete nitriding, ErN requires the highest nitrogenation temperature of at most 1000 °C in N2 flow from ErHx. We obtained the magnetic entropy change ΔS of -14 J/kg K (144 kJ/m3 K, calculated by using the theoretical density of 10.3 g/cm3) at ΔH = 2 T for HoN prepared at the nitrogenation temperature of 1000 °C. This value reached the reported value, indicates that this simple synthesis route without any toxic compounds as a precursor and with normal equipment of an atmospheric furnace without high temperature and pressure can adequately exploit the ability of the rare earth nitride as a magnetic refrigerant for magnetic refrigeration.

A novel beam-bunching technique has been implemented at a heavy-ion linear accelerator facility by installing a compact two-gap prebuncher and a multilayer beam chopper. A pulsed beam of 2 to 4 MHz, having kinetic energy up to 1.1 MeV/u, is realized by bunching a 2 keV/u continuous beam just upstream of the linac. Around 40% of the continuous beam particles are successively gathered in a single microbunch with a time width of around 15 ns in full width at one-tenth maximum. The number of background beam particles over 250 ns just before the bunched beam is well suppressed to less than 10^{-4} of the number of bunched particles. This technique has been adopted to generate intense α-particle beams for nuclear astrophysics experiments.