Elemental substitution effects in multiferroic FeO (: rare earths)

Yoshii, Kenji; Funae, Takeshi*; Mizumaki, Masaichiro*; Ejiri, Hiroki*; Ikeda, Naoshi*; Saito, Hiroyuki; Matsumura, Daiju

Physica Status Solidi (C), 12(6), p.841 - 844, 2015/06

https://doi.org/10.1002/pssc.201400250

We report the effects of elemental substitutions in multiferroic FeO (: Y, Ho-Lu, In). The substitution by nonmagnetic Ga at the Fe site, which has not been reported so far, shows a drastic decrease in the ferrimagnetic transition temperature (). This is plausibly owing to the suppression of magnetic interactions between Fe ions, based on our previous results of other substituted systems such as FeCoO. Dielectric constants near room temperature were comparable to those of FeO. The suppression of dielectric loss in this system is suitable to application. The -site substitution was also attempted by the large R ions such as Dy. The solubility limit was up to about 10% of ions, as confirmed by XRD and EXAFS measurements. was raised by 5-10 K for Dy substitution.

Ion beam analysis of quaternary Heusler alloy Co(MnFe)Si(111) epitaxially grown on Ge(111)

Kawakubo, Yuki*; Noguchi, Masaya*; Hirata, Tomoaki*; Narumi, Kazumasa; Sakai, Seiji; Yamada, Shinya*; Hamaya, Kohei*; Miyao, Masanobu*; Maeda, Yoshihito

Physica Status Solidi (C), 10(12), p.1828 - 1831, 2013/12

https://doi.org/10.1002/pssc.201300367

Optimization of substrate pretreatment and deposition conditions for epitaxial growth of -FeSi film on Si(100)

Yamaguchi, Kenji; Hamamoto, Satoshi*; Hojo, Kiichi

Physica Status Solidi (C), 10(12), p.1699 - 1703, 2013/12

https://doi.org/10.1002/pssc.201300355

Effect of substrate treatment conditions, deposition temperature and deposition rate on the crystallinity of -FeSi films formed on Si substrate was investigated. The substrates were treated with Ne ion beams at room temperature and then annealed at 1073 K prior to film fabrication by means of ion beam sputter deposition (IBSD) method. Combinations of experimental parameters which promote the epitaxial relationship of -FeSi (100) // Si (100) were defined. Complicated dependence of these experimental parameters on the film structure indicated that careful optimization of substrate treatment conditions and deposition parameters would enable to obtain -FeSi films with excellent crystalline properties.

Gutzwiller method for heavy-fermion systems under a magnetic field

Kubo, Katsunori

Physica Status Solidi (C), 10(3), p.544 - 548, 2013/03

https://doi.org/10.1002/pssc.201200762

Measurement of oxygen chemical diffusion in PuO and analysis of oxygen diffusion in PuO and (Pu,U)O

Kato, Masato; Uchida, Teppei; Sunaoshi, Takeo*

Physica Status Solidi (C), 10(2), p.189 - 192, 2013/02

https://doi.org/10.1002/pssc.201200454

Photoluminescence properties of carbon-doped -FeSi nanocrystals

Maeda, Yoshihito; Nishimura, Kentaro*; Nakajima, Takahito*; Matsukura, Bui*; Narumi, Kazumasa; Sakai, Seiji

Physica Status Solidi (C), 9(10-11), p.1884 - 1887, 2012/10

https://doi.org/10.1002/pssc.201200058

We report enhancement of intrinsic photoluminescence (PL) from -FeSi nanocrystals by doping carbon. In the appropriate dose of C ion implantation into the average nanocrystal size of 14 nm, the PL intensity was enhanced by 260% and increase of the exciton binding energy of 1.8 meV in comparison with that of the non-doped nanocrystal. Furthermore, we found that there was a clear correlation between the PL enhancement and increase of the exciton binding energy. This important result suggests that carbon atoms doped in the silicide lattice may play as an isoelectronic trap and probably form bound excitons with stable states as predicted theoretically. We found a new mechanism of the PL enhancement for -FeSi nanocrystals.

Formation of boron nitride ultra-thin films on Si(111)

Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Nath, K. G.*

Physica Status Solidi (C), 9(6), p.1450 - 1453, 2012/06

https://doi.org/10.1002/pssc.201100665

no abstracts in English

Light emitting FET based-on spatially selective doping of Eu in AlGaN/GaN HEMT

Okada, Hiroshi*; Takemoto, Kazumasa*; Oikawa, Fumitake*; Furukawa, Yuzo*; Wakahara, Akihiro*; Sato, Shinichiro; Oshima, Takeshi

Physica Status Solidi (C), 6(Suppl.2), p.S631 - S634, 2009/05

Light emitting field effect transistor (FET) based-on AlGaN/GaN high electron mobility transistor (HEMT) structure with spatially selective doping of rare-earth ions (REIs) as a luminescence center in the channel is proposed and investigated. Fabricated device showed excellent I-V characteristics as a transistor with gate control. By applying a drain bias of 20 V, red emission suggesting a luminescence from Eu ion was clearly observed. Applying a negative bias to the Schottky gate decreased the luminescence intensity.

Reactions of free positrons in low temperature polyethylene; Delayed Ps formation and positron localization

Hirade, Tetsuya; Suzuki, Naoki*; Saito, Fuminori*; Hyodo, Toshio*

Physica Status Solidi (C), 4(10), p.3714 - 3717, 2007/09

https://doi.org/10.1002/pssc.200675742

Positronium (Ps) can be formed by a reaction of trapped electrons and free positrons at low temperatures in molecular solids. While Ps formation by Ore and spur process must be fast, Ps formation by trapped electrons and free positrons is possible even at later positron age. The evidence of this delayed Ps formation was obtained by age-momentum correlation measurement of electron-positron pair annihilation -rays. In this work the parameter curves measured with trapped electrons and no trapped electrons in polyethylene are interpreted by introducing possible positron reactions. Positrons that escape from Ps formation by the Ore and the spur processes have chance to form Ps with trapped electrons. This Ps formation competes with the positron localization resulting from the trapping between molecules or the weakly binding on molecules, ions, or radicals. Assuming the possibility of both the delayed Ps formation and delayed positron trapping and that S-parameters for ortho-Ps and free positrons are the same, we obtain a good fit to the observed time dependent S-parameter curves .

Reflection high-energy positron diffraction study of surface super-structures

Kawasuso, Atsuo; Fukaya, Yuki; Hayashi, Kazuhiko*; Hashimoto, Mie; Ichimiya, Ayahiko

Physica Status Solidi (C), 4(10), p.3924 - 3927, 2007/09

https://doi.org/10.1002/pssc.200675815

In this study, we performed the positron energy loss spectroscopy measurements from several surfaces using energy-filtered reflection high-energy positron diffraction. For Si(111)-77 surface, we observed at least five distinct loss peaks. The interval of energy loss peaks is approximately 10 eV, which corresponds to the surface plasmon loss energy of silicon. The positron energy loss spectra are well-approximated by the Poisson distribution. The average excitation number of surface plasmon is 2.6 under the total reflection condition. This number is similar to what expected for electrons at zero glancing angle. Thus, positrons lose their energy due to surface plasmon excitation much more sufficiently than electrons. We found that the specular spot is broadened in the total reflection region especially at the tail part due to plasmon excitation.