Electric field control of nonvolatile four-state magnetization at room temperature

We find the realization of large converse magnetoelectric (ME) effects at room temperature in a magnetoelectric hexaferrite Ba0.52Sr2.48Co2Fe24O41 single crystal, in which rapid change of electric polarization in low magnetic fields (about 5 mT) is coined to a large ME susceptibility of 3200 ps/m. The modulation of magnetization then reaches up to 0.62μ(B)/f.u. in an electric field of 1.14 MV/m. We find further that four ME states induced by different ME poling exhibit unique, nonvolatile magnetization versus electric field curves, which can be approximately described by an effective free energy with a distinct set of ME coefficients.     

Self‐formed Schottky barrier induced selector‐less RRAM for cross‐point memory applications

We propose a selector‐less Pr_0.7Ca_0.3MnO₃ (PCMO) based resistive‐switching RAM (RRAM) for high‐density cross‐point memory array applications. First, we investigate the inhomogeneous barrier with an effective barrier height (Φ_eff), i.e., self‐formed Schottky barrier. In addition, a scalable 4F² selector‐less cross‐point 1 kb RRAM array has been successfully fabricated, demonstrating set, reset, and read operation for high cell efficiency and high‐density memory applications. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Cutoff characteristics of dielectric-filled circular holes embedded in dispersive plasmonic medium

The cutoff characteristics of dielectric-filled circular holes embedded in a dispersive plasmonic medium are investigated. Since two distinctive operating modes, surface plasmon polariton and circular waveguide modes, can exist in the slow and fast wave regions, respectively, the cutoff characteristics for each are separately investigated for linear and radial polarizations of the guided fields. As a result, the cutoff wavelengths for the linear and radial polarizations with very small subwavelength hole radii are found to be limited by the plasma resonance wavelength and plasma wavelength, which in turn are dependent and independent, respectively, of the dielectric constant of the dielectric filler material.     

High-spin states in neutron-rich 102Mo nucleus

High-spin states in neutron-rich 102Mo nucleus have been studied by measuring the prompt γ-rays in the spontaneous fission of 252Cf. The previous level scheme has been updated and some new levels and transitions are identified. The one-phonon γ-band is expanded and a band head level of the two-phonon γ-band is proposed. The systematic characteristics of yrast bands, one-phonon γ-bands, two-phonon γ-bands and quasi-particle bands in 102Mo, 104Mo and 106Mo are discussed.     

Technical Reports: Time-Resolved Activities at the Advanced Photon Source Requiring the Pulsed Structure of the X-ray Beam

Scientific research in the time domain using the pulsed structure of the X-ray beams from a third-generation synchrotron source, such as the Advanced Photon Source (APS), has become a major interest among synchrotron users. The traditional material science, chemistry, and biology communities are getting an early glimpse of the potential impact of fast time-resolved X-ray studies. The scientific disciplines that have benefited from these studies include atomic and molecular physics, biology, chemical science, condensed matter physics, engineering science, environmental science, material science, and nuclear science. Technically, the turn-key-type femtosecond (fs) optical lasers with high peak power, used as pumps in many X-ray pump-probe experiments, have only recently become available.     

Multiparameter kinetic analysis of alkaline hydrolysis of a series of aryl diphenylphosphinothioates: models for P=S neurotoxins

Alkaline hydrolysis of a series of X‐substituted‐phenyl diphenylphosphinothioates ( 2a‐i ) in 80 mol%/20 mol% DMSO at 25.0 ± 0.1°C has been studied kinetically and assessed through a multiparameter approach. Substrates 2a to 2i are approximately 12 to 22 times less reactive than their P=O analogues 1a to 1i (ie, the thio effect). The Brønsted‐type plot for the reactions of 2a to 2i is linear with β_lg = ?0.43, consistent with a concerted mechanism. Hammett plots correlated with σ^o and σ^? constants also support a concerted mechanism; the Yukawa‐Tsuno plot results in an excellent linear correlation with ρ_X = 1.26 and r = 0.30, indicating that expulsion of the leaving group occurs in the rate‐determining step (RDS). The ΔH^? value increases from 10.5 to 11.7 and 13.9 kcal/mol as substituent X in the leaving group changes from 3,4‐(NO₂)₂ to 4‐NO₂ and H, in turn, while TΔS^? remains constant at ?6.0 kcal/mol. The strong dependence of ΔH^? on the electronic nature of substituent X also indicates that the leaving group departs in the RDS. The reaction mechanism and origin of the thio effect are discussed by comparison of the current kinetic results with those reported for the reactions of 1a to 1i . The results suggest that for useful OP neurotoxins the mechanism of abiotic hydrolysis is concerted (with varying degrees of asynchronicity) when the substrate bears good leaving groups.     

Soft X‐ray absorption spectroscopy and resonant inelastic X‐ray scattering spectroscopy below 100 eV: probing first‐row transition‐metal M‐edges in chemical complexes

X‐ray absorption and scattering spectroscopies involving the 3d transition‐metal K‐ and L‐edges have a long history in studying inorganic and bioinorganic molecules. However, there have been very few studies using the M‐edges, which are below 100 eV. Synchrotron‐based X‐ray sources can have higher energy resolution at M‐edges. M‐edge X‐ray absorption spectroscopy (XAS) and resonant inelastic X‐ray scattering (RIXS) could therefore provide complementary information to K‐ and L‐edge spectroscopies. In this study, M_2,3‐edge XAS on several Co, Ni and Cu complexes are measured and their spectral information, such as chemical shifts and covalency effects, are analyzed and discussed. In addition, M_2,3‐edge RIXS on NiO, NiF₂ and two other covalent complexes have been performed and different d–d transition patterns have been observed. Although still preliminary, this work on 3d metal complexes demonstrates the potential to use M‐edge XAS and RIXS on more complicated 3d metal complexes in the future. The potential for using high‐sensitivity and high‐resolution superconducting tunnel junction X‐ray detectors below 100 eV is also illustrated and discussed.     

Engineering silicon-based photonic crystal cavities for NV-center quantum information processing

Silicon slab photonic crystal micro cavities designed for of-resonant coupling to nitrogen vacancy (NV) centers were simulated and fabricated. FDTD-simulations show the partial density of states spectrally near the NV-center electric dipole transition can be tuned to reduce decoherence of an excited NV-center despite this transition being above the silicon electronic band gap. The partial density of states at the NV-center transition can be made to dip below half of the free-space partial density of states without significantly affecting the cavity mode quality factor. These promising results sustain the merits of using silicon as a base photonic crystal material for quantum information processing even when integrated emitters radiate above the electronic band gap of silicon.     

Structure and dynamics of dense monolayers of no adsorbed on Rh(111) in equilibrium with the gas phase in the Torr pressure range

Using scanning tunneling microscopy, we show the phase transition between new structures of NO on Rh(111) in equilibrium with the gas phase near 300 K, in the Torr pressure range. Two phases with (2 x 2) and (3 x 3) periodicity transform into each other as the pressure and temperature change around the equilibrium P-T line. By measuring P and T at coexistence, we determined the heat of adsorption in the (3 x 3) structure. From the phase boundary dynamics, the activation energy barrier between phases were estimated. The results demonstrate that unique information can be obtained from high-pressure and high-temperature studies.