Ionization Source of a Minor-axis Cloud in the Outer Halo of M82

The M82 `cap' is a gas cloud at a projected radius of 11.6 kpc along the minor axis of this well known superwind source. The cap has been detected in optical line emission and X-ray emission and therefore provides an important probe of the wind energetics. In order to investigate the ionization source of the cap, we observed it with the Kyoto3DII Fabry-Perot instrument mounted on the Subaru Telescope. Deep continuum, Ha, [NII]6583/Ha, and [SII]6716,6731/Ha maps were obtained with sub-arcsecond resolution. The superior spatial resolution compared to earlier studies reveals a number of bright Ha emitting clouds within the cap. The emission line widths (< 100 km s^-1 FWHM) and line ratios in the newly identified knots are most reasonably explained by slow to moderate shocks velocities (v_shock = 40--80 km s^-1) driven by a fast wind into dense clouds. The momentum input from the M82 nuclear starburst region is enough to produce the observed shock. Consequently, earlier claims of photoionization by the central starburst are ruled out because they cannot explain the observed fluxes of the densest knots unless the UV escape fraction is very high (f_esc > 60%), i.e., an order of magnitude higher than observed in dwarf galaxies to date. Using these results, we discuss the evolutionary history of the M82 superwind. Future UV/X-ray surveys are expected to confirm that the temperature of the gas is consistent with our moderate shock model.Comment: 7 pages, 5 figures, 2 tables; Accepted for publication in Ap

Binary systems of discotic liquid crystalline semiconductors toward solution-processing thin film devices

SPIE OPTO, 2012, San Francisco, California, United StatesY. Shimizu, Y. Matsuda, F. Nekelson, Y. Miyake, H. Yoshida, A. Fujii, and M. Ozaki "Binary systems of discotic liquid crystalline semiconductors toward solution-processing thin film devices", Proc. SPIE 8279, Emerging Liquid Crystal Technologies VII, 82790G (10 February 2012). DOI: https://doi.org/10.1117/12.91354

Liquid crystalline phthalocyanines as a self-assembling organic semiconductor for solution-processing thin film devices

SPIE OPTO, 2011, San Francisco, California, United StatesY. Miyake, T. Hori, H. Yoshida, H. Monobe, A. Fujii, M. Ozaki, and Y. Shimizu "Liquid crystalline phthalocyanines as a self-assembling organic semiconductor for solution-processing thin film devices", Proc. SPIE 7955, Emerging Liquid Crystal Technologies VI, 795505 (2 February 2011). DOI: https://doi.org/10.1117/12.87371

Low-temperature Synthesis of FeTe0.5Se0.5 Polycrystals with a High Transport Critical Current Density

We have prepared high-quality polycrystalline FeTe0.5Se0.5 at temperature as low as 550{\deg}C. The transport critical current density evaluated by the current-voltage characteristics is over 700 A/cm2 at 4.2 K under zero field, which is several times larger than FeTe0.5Se0.5 superconducting wires. The critical current density estimated from magneto-optical images of flux penetration is also similar to this value. The upper critical field of the polycrystalline FeTe0.5Se0.5 at T = 0 K estimated by Werthamer-Helfand-Hohenberg theory is 585 kOe, which is comparable to that of single crystals. This study gives some insight into how to improve the performance of FeTe0.5Se0.5 superconducting wires.Comment: 12 pages, 6 figure

Amplified spontaneous emission and lasing in conducting polymers and fluorescent dyes in opals as photonic crystals

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in K. Yoshino, S. Tatsuhara, Y. Kawagishi, M. Ozaki, A. A. Zakhidov, and Z. V. Vardeny, Appl. Phys. Lett. 74, 2590 (1999) and may be found at https://doi.org/10.1063/1.123907

Fermiological Interpretation of Superconductivity/Non-superconductivity of FeTe_{1-x}Se_{x} Thin Crystal Determined by Quantum Oscillation Measurement

We have successfully observed quantum oscillation (QO) for FeTe_{1-x}Se_{x}. QO measurements were performed using non-superconducting and superconducting thin crystals of FeTe_{0.65}Se_{0.35} fabricated by the scotch-tape method. We show that the Fermi surfaces (FS) of the non-superconducting crystal are in good agreement with the rigid band shift model based on electron doping by excess Fe while that of the superconducting crystal is in good agreement with the calculated FS with no shift. From the FS comparison of both crystals, we demonstrate the change of the cross-sectional area of the FS, suggesting that the suppression of the FS nesting with the vector Q_{s} = (\pi, \pi) due to excess Fe results in the disappearance of the superconductivity.Comment: 8 pages, 4 figure

Observation of inhibited spontaneous emission and stimulated emission of rhodamine 6G in polymer replica of synthetic opal

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in K. Yoshino, S. B. Lee,b) S. Tatsuhara, Y. Kawagishi, and M. Ozaki, and A. A. Zakhidov, Appl. Phys. Lett. 73, 3506 (1998) and may be found at https://doi.org/10.1063/1.122819