Detecting halfmetallic electronic structures of spintronic materials in a magnetic field

Band-gap engineering is one of the fundamental techniques in semiconductor technology and also applicable in next generation spintronics using the spin degree of freedom. To fully utilize the spintronic materials, it is essential to optimize the spin-dependent electronic structures in the operando conditions by applying magnetic and/or electric fields. Here we present an advanced spectroscopic technique to probe the spin-polarized electronic structures by using magnetic circular dichroism (MCD) in resonant inelastic soft X-ray scattering (RIXS) under an external magnetic field. Thanks to the spin-selective dipole-allowed transitions in RIXS-MCD, we have successfully demonstrated the direct evidence of the perfectly spin-polarized electronic structures for the prototypical halfmetallic Heusller alloy \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {Co}_2\hbox {MnSi}$$\end{document}Co2MnSi. RIXS-MCD is a promising tool to probe the spin-dependent carriers and band-gap induced in the buried magnetic layers in an element specific way under the operando conditions.

Tensile-Strain-Dependent Spin States in Epitaxial LaCoO_{3} Thin Films

The spin states of Co^{3+} ions in perovskite-type LaCoO_{3}, governed by the complex interplay between the electron-lattice interactions and the strong electron correlations, still remain controversial due to the lack of experimental techniques which can directly detect them. In this Letter, we revealed the tensile-strain dependence of spin states, i.e., the ratio of the high- and low-spin states, in epitaxial thin films and a bulk crystal of LaCoO_{3} via resonant inelastic soft x-ray scattering. A tensile strain as small as 1.0% was found to realize different spin states from that in the bulk.

Probing the OH Stretch in Different Local Environments in Liquid Water

We use resonant inelastic X-ray scattering (RIXS) to resolve vibrational losses corresponding to the OH stretch where the X-ray absorption process allows us to selectively probe different structural subensembles in liquid water. The results point to a unified interpretation of X-ray and vibrational spectroscopic data in line with a picture of two classes of structural environments in the liquid at ambient conditions with predominantly close-packed high-density liquid (HDL) and occasional local fluctuations into strongly tetrahedral low-density liquid (LDL).

Interface electronic structure at the topological insulator-ferrimagnetic insulator junction

An interface electron state at the junction between a three-dimensional topological insulator film, Bi₂Se₃, and a ferrimagnetic insulator film, Y₃Fe₅O₁₂ (YIG), was investigated by measurements of angle-resolved photoelectron spectroscopy and x-ray absorption magnetic circular dichroism. The surface state of the Bi₂Se₃ film was directly observed and localized 3d spin states of the Fe³⁺ in the YIG film were confirmed. The proximity effect is likely described in terms of the exchange interaction between the localized Fe 3d electrons in the YIG film and delocalized electrons of the surface and bulk states in the Bi₂Se₃ film.

Electron-Phonon Coupling in the Bulk of Anatase TiO2 Measured by Resonant Inelastic X-Ray Spectroscopy

We investigate the polaronic ground state of anatase TiO2 by bulk-sensitive resonant inelastic x-ray spectroscopy (RIXS) at the Ti L3 edge. We find that the formation of the polaron cloud involves a single 95 meV phonon along the c axis, in addition to the 108 meV ab-plane mode previously identified by photoemission. The coupling strength to both modes is the same within error bars, and it is unaffected by the carrier density. These data establish RIXS as a directional bulk-sensitive probe of electron-phonon coupling in solids.

Existence of orbital order and its fluctuation in superconducting Ba(Fe(1-x)Co(x))2As2 single crystals revealed by x-ray absorption spectroscopy

We performed temperature dependent x-ray linear dichroism (XLD) experiments on an iron pnictide system, Ba(Fe(1-x)Co(x))2As2 with x=0.00, 0.05, 0.08, and 0.10 to experimentally verify the existence of orbital ordering (OO). Substantial XLD was observed in polarization dependent x-ray absorption spectra of Fe L edges. By exploiting the difference in the temperature dependent behaviors, OO, and structure contributions to XLD could be clearly separated. The observed OO signal indicates different occupation numbers for d(yz) and d(zx) orbitals and supports the existence of ferro-OO. The results are also consistent with the theoretical prediction. Moreover, we find substantial OO signal well above the structural and magnetic transition temperatures, which suggests the existence of strong OO fluctuations up to high temperatures.

Out-of-plane nesting driven spin spiral in ultrathin Fe/Cu(001) films

Epitaxial ultrathin Fe films on fcc Cu(001) exhibit a spin spiral (SS), in contrast to the ferromagnetism of bulk bcc Fe. We study the in-plane (IP) and out-of-plane (OP) Fermi surfaces (FSs) of the SS in 8 monolayer Fe/Cu(001) films using energy-dependent soft-x-ray momentum-resolved photoemission spectroscopy. We show that the SS originates in nested regions confined to OP FSs, which are drastically modified compared to IP FSs. From precise reciprocal-space maps in successive zones, we obtain the associated real space compressive strain of 1.5+/-0.5% along c axis. An autocorrelation analysis quantifies the incommensurate ordering vector q=(2pi/a)(0,0, approximately 0.86), favoring a SS and consistent with magneto-optic Kerr effect experiments. The results reveal the importance of IP and OP FS mapping for ultrathin films.

Isolating Single-Wall Carbon Nanohorns as Small Aggregates through a Dispersion Method

An approach to isolating small aggregates of single-wall carbon nanohorns (SWNHs) is presented. SWNHs are ultrasonically treated in an aqueous solution of surfactant, resulting in dispersion of SWNH aggregates. Subsequent centrifuging enables the separation of small aggregates from larger aggregates or agglomerations and removal of graphitic particles (GG balls), the main impurity. The SWNHs obtained in this way were purified and formed small aggregates, thus exhibiting characteristics superior to those of SWNHs before treatment. We believe that the ability to isolate small SWNH aggregates in an aqueous solution should contribute to their application in the fields of biological sensing and drug delivery systems.

[Anesthetic management of a patient with a huge ovarian tumor]

We managed a patient with a huge ovarian tumor (15 kg). The patient was a 50-year-old woman and could not take the supine position because of the tumor causing respiratory embarrassment. An epidural catheter was inserted 3 cm cephalad via the Th 11-12 interspace in the right lateral position. Three milliliters of 1% mepivacaine was injected epidurally for test dose and produced hypesthesia of Th 9-12 five min after the injection. Additional 3 ml of 1% mepivacaine was injected epidurally, which widened the hypesthesia to Th 5-L 2. Intra-arterial pressure was monitored continuously. Under epidural anesthesia without sedation, 11,000 ml of fluid was suctioned slowly from the cyst in 20 min, during which time remarkable hemodynamic derangement did not occur. The patient was turned into the supine position and the trachea was intubated. Laparotomy was performed under general anesthesia. During the surgery, respiratory and hemodynamic conditions were stable. On the following day, chest radiography demonstrated an abnormal shadow in the lower lobe of the right lung. It disappeared the next day without any treatment. Anesthetic management of patients with huge abdominal tumor is also discussed.

Prolonged P-R interval in a male with 47,XYY karyotype

A 47,XYY male with an extremely prolonged P-R interval (0.42 sec) on the electrocardiograph is described. There was also a secondary R wave in lead V1. He had no past history of heart disease and no cardiac abnormality on physical examination.