Band structures of 4 and 5 materials studied by angle-resolved photoelectron spectroscopy

Fujimori, Shinichi

Journal of Physics; Condensed Matter, 28(15), p.153002_1 - 153002_31, 2016/04

https://doi.org/10.1088/0953-8984/28/15/153002

Phonons of Fe-based superconductor CaPtAs(FePtAs)

Ikeuchi, Kazuhiko*; Kobayashi, Yoshiaki*; Suzukia, Kazunori*; Ito, Masayuki*; Kajimoto, Ryoichi; Bourges, P.*; Christianson, A. D.*; Nakamura, Hiroki; Machida, Masahiko; Sato, Masatoshi*

Journal of Physics; Condensed Matter, 27(46), p.465701_1 - 465701_7, 2015/11

https://doi.org/10.1088/0953-8984/27/46/465701

We report the results of inelastic neutron scattering measurements on particular phonons of a superconducting (SC) CaPtAs(FePtAs) with the onset transition temperature K to investigate mainly what roles orbital fluctuation plays in Cooper pairing, where we observed a slight softening of the in-plane transverse acoustic mode corresponding to the elastic constant . This softening starts at temperature well above the SC , as decreases. An anomalously strong change of the scattering intensity of in-plane optical modes was observed at the M point of the pseudo tetragonal reciprocal space in the range of 35 40 meV with decreasing from far above . Because this region mainly corresponds to the motion of Fe and As atoms in the FeAs planes, the finding presents information on the coupling between the orbital fluctuation of Fe electrons and the lattice system, useful for studying the possible roles of orbital fluctuation in the pairing mechanism and/or the appearance of the so-called nematic phase.

Longitudinal spin Seebeck effect; From fundamentals to applications

Uchida, Kenichi*; Ishida, Masahiko*; Kikkawa, Takashi*; Kirihara, Akihiro*; Murakami, Tomoo*; Saito, Eiji

Journal of Physics; Condensed Matter, 26(34), p.343202_1 - 343202_15, 2014/08

https://doi.org/10.1088/0953-8984/26/34/343202

Weak itinerant antiferromagnetism in PuIn explored using In nuclear quadrupole resonance

Chudo, Hiroyuki; Koutroulakis, G.*; Yasuoka, Hiroshi; Bauer, E. D.*; Tobash, P. H.*; Mitchell, J. N.*; Thompson, J. D.*

Journal of Physics; Condensed Matter, 26(3), p.036001_1 - 036001_5, 2014/01

https://doi.org/10.1088/0953-8984/26/3/036001

The results of In nuclear quadrupole resonance (NQR) measurements on PuIn are reported. Three of the four NQR lines of In expected for nuclear spin =9/2 are observed. The equal spacing of these lines at 20 K yields the NQR frequency of =10.45 MHz, and the asymmetry parameter of the electric field gradient, =0. The NQR line profile and the nuclear spin-lattice relaxation rate display an abrupt change at 14 K, which is associated with the onset of long-range antiferromagnetic order. The temperature dependences of the staggered magnetization , extracted from the NQR spectra, and below =14 K are well explained by the self-consistent renormalization (SCR) theory for spin fluctuations. In addition, scaling between and is also consistent with the predictions of SCR theory, providing further evidence that PuIn is a weak itinerant antiferromagnet in which spin fluctuations around the antiferromagnetic wave vector play a major role in the system's behavior at finite temperatures.

Perpendicular magnetic anisotropy with enhanced orbital moments of Fe adatoms on a topological surface of BiSe

Ye, M.*; Kuroda, Kenta*; Takeda, Yukiharu; Saito, Yuji; Okamoto, Kazuaki*; Zhu, S.-Y.*; Shirai, Kaito*; Miyamoto, Koji*; Arita, Masashi*; Nakatake, Masashi*; et al.

Journal of Physics; Condensed Matter, 25(23), p.232201_1 - 232201_5, 2013/06

https://doi.org/10.1088/0953-8984/25/23/232201

no abstracts in English

Observation of a pressure-induced As-As hybridization associated with a change in the electronic state of Fe in the tetragonal phase of EuFeAs

Kobayashi, Hisao*; Ikeda, Shugo*; Sakaguchi, Yui*; Yoda, Yoshitaka*; Nakamura, Hiroki; Machida, Masahiko

Journal of Physics; Condensed Matter, 25(2), p.022201_1 - 022201_6, 2013/01

https://doi.org/10.1088/0953-8984/25/2/022201

The electronic and vibrational properties of EuFeAs in the tetragonal phase between 0 and 5 GPa have been investigated using Fe Mssbauer spectroscopy and Fe nuclear resonance inelastic scattering, respectively. We find a discontinuous increase of the center shift around 2.3 GPa, reflecting a change of the electronic state of Fe, and above 2.5 GPa a softening of the optical phonon modes associated with an increase of the relative volume of the FeAs tetrahedron in the unit cell. Our findings reveal that an effective As-As hybridization along the c axis appears at approximately 2.3 GPa in the tetragonal phase of EuFeAs, along with a change in the electronic state of Fe, causing bulk superconductivity to appear at a low temperature. Consequently, the change in the electronic state of the Fe atom and the effective As-As hybridization play key roles in the pressure-induced superconductivity in the tetragonal phase of AFeAs.

A Theoretical study of the reactivity of CuO(111) surfaces; The Case of NO dissociation

Kishi, Hirofumi*; Padama, A. A. B.*; Arevalo, R. L.*; Moreno, J. L. V.*; Kasai, Hideaki*; Taniguchi, Masashi*; Uenishi, Mari*; Tanaka, Hirohisa*; Nishihata, Yasuo

Journal of Physics; Condensed Matter, 24(26), p.262001_1 - 262001_5, 2012/07

https://doi.org/10.1088/0953-8984/24/26/262001

no abstracts in English

X-ray fluorescence holography

Hayashi, Koichi*; Happo, Naohisa*; Hosokawa, Shinya*; Hu, W.; Matsushita, Tomohiro*

Journal of Physics; Condensed Matter, 24(9), p.093201_1 - 093201_15, 2012/03

https://doi.org/10.1088/0953-8984/24/9/093201

Electronic and local structures of BiFeO films

Yoneda, Yasuhiro; Sakamoto, Wataru*

Journal of Physics; Condensed Matter, 23(1), p.015902_1 - 015902_5, 2011/01

https://doi.org/10.1088/0953-8984/23/1/015902

The electric structure of BiFeO (BFO), BiFeO-PbTiO solid solution (BFO-PT), and Mn-doped BFO-PT (BFM-PT) films fabricated by chemical solution deposition were investigated by X-ray absorption fine structure (XAFS). The valence fluctuation of iron atoms was closely connected with the leakage current properties. The charge fluctuated BFO film showed leaky feature, and the charge ordered BFO-PT and BFM-PT films were improved leakage current property. The valence fluctuation of iron atoms can be controlled by Mn and Ti substitutions.

Epitaxial growth of largely mismatched crystals on H-terminated Si (111) surfaces

Asaoka, Hidehito

Journal of Physics; Condensed Matter, 22(47), p.474007_1 - 474007_7, 2010/12

https://doi.org/10.1088/0953-8984/22/47/474007

A strontium or strontium oxide epitaxial layer was grown using a monoatomic buffer layer of hydrogen on silicon, in spite of a huge lattice mismatch. The onset of the initial growth stage of strontium crystals occur with only one atomic layer deposition. To investigate the growth mechanism in the highly mismatched system, combination analysis using neutron reflection, reflection high-energy electron diffraction, X-ray photoelectron spectra, and stress measurements is employed. The interface structure has opened up a new way to fabricate novel heterostructures, consisting of various kinds of one-, two- or three-dimensional materials for future silicon-based technology.