J. Okamoto

Nature of magnetic coupling between Mn ions in as-grown Ga$_{1-x}$Mn$_{x}$As studied by x-ray magnetic circular dichroism (2008)

Takeda, Y., Kobayashi, M., Okane, T., Ohkochi, T., Okamoto, J., Saitoh, Y., ...

The magnetic properties of as-grown Ga$_{1-x}$Mn$_{x}$As have been investigated by the systematic measurements of temperature and magnetic field dependent soft x-ray magnetic circular dichroism...

Soft x-ray magnetic circular dichroism study of Ca_1-xSr_xRuO_3 across the ferromagnetic quantum phase transition (2007)

Okamoto, J., Okane, T., Saitoh, Y., Terai, K., Muramatsu, Y., ...

Ca_1-xSr_xRuO_3, which is ferromagnetic for Sr concentration x > 0.3, has been studied by x-ray magnetic circular dichroism (XMCD) in Ru 3p and O 1s core-level x-ray absorption. XMCD signals appear...

Symmetry of Multiferroicity in a Frustrated Magnet TbMn$_2$O$_5$ (2007)

Okamoto, J., Huang, D. J., Chao, K. S., Park, S., ...

Based on measurements of soft x-ray magnetic scattering and symmetry considerations, we demonstrate that the magnetoelectric effect in TbMn$_2$O$_5$ arises from an internal field determined by...

Soft x-ray magnetic circular dichroism study of weakly ferromagnetic Zn$_{1-x}$V$_x$O thin film (2006)

Ishida, Y., Hwang, J. I., Kobayashi, M., Takeda, Y., Mamiya, K., Okamoto, J., ...

We performed a soft x-ray magnetic circular dichroism (XMCD) study of a Zn$_{1-x}$V$_x$O thin film which showed small ferromagnetic moment. Field and temperature dependences of V 2$p$ XMCD signals...

Evolution of the electronic structure across the filling-control and bandwidth-control metal-insulator transitions in pyrochlore-type Ru oxides (2006)

Okamoto, J., Okane, T., Fujimori, A., Abbate, M., Yoshii, S., ...

We have performed photoemission and soft x-ray absorption studies of pyrochlore-type Ru oxides, namely, the filling-control system Sm$_{2-x}$Ca$_x$Ru$_2$O$_7$ and the bandwidth-control system...

Thermo-sensitive colloidal crystals of silica spheres in the presence of large spheres with poly (N-isopropyl acrylamide) shells (2006)

Okubo, T., Mizutani, T., Okamoto, J., Kimura, K., Tsuchida, A., Tauer, K., ...

Characterization of Magnetic Components in the Diluted Magnetic Semiconductor Zn$_{1-x}$Co$_x$O by X-ray Magnetic Circular Dichroism (2005)

Kobayashi, M., Ishida, Y., Hwang, J. L., Mizokawa, T., Fujimori, A., Mamiya, K., ...

We report on the results of x-ray absorption (XAS), x-ray magnetic circular dichroism (XMCD), and photoemission experiments on {\it n}-type Zn$_{1-x}$Co$_x$O ($x=0.05$) thin film, which shows...

High-energy spectroscopic study of the III-V nitride-based diluted magnetic semiconductor Ga$_{1-x}$Mn$_{x}$N (2005)

Hwang, J. I., Ishida, Y., Kobayashi, M., Hirata, H., Takubo, K., Mizokawa, T., ...

We have studied the electronic structure of the diluted magnetic semiconductor Ga$_{1-x}$Mn$_{x}$N ($x$ = 0.0, 0.02 and 0.042) grown on Sn-doped $n$-type GaN using photoemission and soft x-ray...

Orbital Symmetry and Electron Correlation in Na_{x}CoO_2 (2004)

Wu, W. B., Huang, D. J., Okamoto, J., Tanaka, A., Chou, F. C., ...

Measurements of polarization-dependent soft x-ray absorption reveal that the electronic states determining the low-energy excitations of Na$_{x}$CoO$_2$ have predominantly $a_{1g}$ symmetry with...

Temperature dependence of hyperfine magnetic fields in Fe-Co alloys (1990)

Hamdeh, H. H., Okamoto, J., Fultz, B.

A Mössbauer spectrometry study of bcc Fe-Co alloys was performed to measure the 57Fe hyperfine-field parameters from 77 to 900 K. The temperature dependence of the 57Fe hyperfine magnetic field in...