Noma, Yuichiro*; Kotegawa, Hisashi*; Kubo, Tetsuro*; To, Hideki*; Harima, Hisatomo*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*; Ito, Kohei*; Nakamura, Ai*; et al.
Journal of the Physical Society of Japan, 90(7), p.073707_1 - 073707_5, 2021/07
Yoshida, Shogo*; Koyama, Takehide*; Yamada, Haruhiko*; Nakai, Yusuke*; Ueda, Koichi*; Mito, Takeshi*; Kitagawa, Kentaro*; Haga, Yoshinori
Physical Review B, 103(15), p.155153_1 - 155153_5, 2021/04
Haga, Yoshinori; Sugai, Takashi*; Matsumoto, Yuji*; Yamamoto, Etsuji
JPS Conference Proceedings (Internet), 29, p.013003_1 - 013003_5, 2020/02
Nakamura, Shota*; Sakakibara, Toshiro*; Shimizu, Yusei*; Kittaka, Shunichiro*; Kono, Yohei*; Haga, Yoshinori; Pospisil, J.; Yamamoto, Etsuji
Progress in Nuclear Science and Technology (Internet), 5, p.123 - 127, 2018/11
Motoyama, Gaku*; Haga, Yoshinori; Yamaguchi, Akira*; Kawasaki, Ikuto*; Sumiyama, Akihiko*; Yamamura, Tomoo*
Progress in Nuclear Science and Technology (Internet), 5, p.157 - 160, 2018/11
Iha, Wataru*; Yara, Tomoyuki*; Ashitomi, Yosuke*; Kakihana, Masashi*; Takeuchi, Tetsuya*; Honda, Fuminori*; Nakamura, Ai*; Aoki, Dai*; Gochi, Jun*; Uwatoko, Yoshiya*; et al.
Journal of the Physical Society of Japan, 87(6), p.064706_1 - 064706_14, 2018/06
Noma, Yuichiro*; Kotegawa, Hisashi*; Kubo, Tetsuro*; To, Hideki*; Harima, Hisatomo*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*; Ito, Kohei*; Haller, E. E.*; et al.
Journal of the Physical Society of Japan, 87(3), p.033704_1 - 033704_5, 2018/03
Saito, Yuji; Yasui, Akira*; Fuchimoto, Hiroto*; Nakatani, Yasuhiro*; Fujiwara, Hidenori*; Imada, Shin*; Narumi, Yasuo*; Kindo, Koichi*; Takahashi, Minoru*; Ebihara, Takao*; et al.
Physical Review B, 96(3), p.035151_1 - 035151_5, 2017/07
We revisit the delocalized character of the 4 states of CeFe in the ferromagnetically ordered phase by X-ray magnetic circular dichroism (XMCD) in X-ray absorption spectroscopy (XAS) with improved data quality using single crystals. Surprisingly, the Ce XMCD spectral shape changes significantly as a function of temperature and applied magnetic field, with no concomitant changes in the spectral shape of the Ce XAS as well as the Fe XAS and XMCD. This unusual behavior is characterized by the states in a 4 configuration mixed into the ground state. Such extreme sensitivity of the Ce 4 states to the external perturbations can be related to the magnetic instability toward an antiferromagnetic phase in CeFe. Our experimental data presented here provide valuable insights into the underlying physics in strongly-hybridized ferromagnetic Ce compounds.
Pospisil, J.; Gochi, Jun*; Haga, Yoshinori; Honda, Fuminori*; Uwatoko, Yoshiya*; Tateiwa, Naoyuki; Kambe, Shinsaku; Nagasaki, Shoko*; Homma, Yoshiya*; Yamamoto, Etsuji
Journal of the Physical Society of Japan, 86(4), p.044709_1 - 044709_6, 2017/04
Saito, Yuji; Fujiwara, Hidenori*; Yamaguchi, Takashi*; Nakatani, Yasuhiro*; Mori, Takeo*; Fuchimoto, Hiroto*; Kiss, Takayuki*; Yasui, Akira*; Miyawaki, Jun*; Imada, Shin*; et al.
Journal of the Physical Society of Japan, 85(11), p.114713_1 - 114713_7, 2016/11
We report on the electronic structures of ferromagnetic CeAgSb using soft X-ray absorption (XAS), magnetic circular dichroism (XMCD), and angle-resolved photoemission (ARPES) spectroscopies. The Ce XAS spectra show very small satellite structures, reflecting a strongly localized character of the Ce 4 electrons. The linear dichroism effects in the Ce XAS spectra demonstrate the ground-state Ce 4 symmetry of , the spatial distribution of which is directed along the -axis. Nevertheless, ARPES spectra at the Ce 3-4 resonance show the momentum dependence of the intensity ratio between Ce 4 and 4 peaks in a part of the Brillouin zone, suggesting the non negligible momentum-dependent hybridization effect between the Ce 4 and the conduction electrons. This is associated with the moderate mass enhancement in CeAgSb.
Matsuda, Tatsuma; Haga, Yoshinori; Ikeda, Shugo; Galatanu, A.; Yamamoto, Etsuji; Shishido, Hiroaki*; Yamada, Mineko*; Yamaura, Junichi*; Hedo, Masato*; Uwatoko, Yoshiya*; et al.
Journal of the Physical Society of Japan, 74(5), p.1552 - 1556, 2005/05
We have succeeded in growing a high-quality single crystal of UCuSi with the tetragonal structure by the Sn-flux method and measured the electrical resistivity, magnetic susceptibility, magnetization and specific heat. UCuSi is found to order antiferromagnetically below = 106 K, and follows a successive ferromagnetic ordering at = 100 K. The magnetic properties are highly anisotropic, reflecting the crystal structure. An easy-axis of magnetization is found to be the  direction (-axis) both in the antiferromagnetic and ferromagnetic phases, while the  direction (-axis) corresponds to the hard-axis in magnetization. The magnetization curve in the antiferromagnetic phase indicates a clear metamagnetic transition at a low field of about 1 kOe and changes smoothly into a ferromagnetic magnetization curve below = 100 K. The saturation moment is determined as 1.75/U at 2 K. The electronic specific heat coefficient is also determined as 20 mJ/Kmol.
Okane, Tetsuo; Okamoto, Jun; Mamiya, Kazutoshi; Fujimori, Shinichi; Saito, Yuji; Muramatsu, Yasuji; Fujimori, Atsushi; Ochiai, Akira*
Physica B; Condensed Matter, 345(1-4), p.221 - 224, 2004/03
Magnetic circular dichroism (MCD) has been measured at the U absorption edges of ferromagnetic uranium monochalcogenides US, USe and UTe. The MCD signals are weaker in US than in USe and UTe. Both the spin and orbital moments are increased in going from US to USe, and then reduced from USe to UTe.
Kaneko, Koji; Metoki, Naoto; Bernhoeft, N.*; Lander, G. H.; Ishii, Yoshinobu; Ikeda, Shugo; Tokiwa, Yoshifumi; Haga, Yoshinori; Onuki, Yoshichika
Physical Review B, 68(21), p.214419_1 - 214419_9, 2003/12
The crystal structure, lattice strain due to the antiferromagnetic ordering and magnetic form factor in the itinerant 5 compounds UTGa (T: Ni, Pd, Pt) have been studied by neutron scattering. High-resolution powder diffraction revealed that the tetragonality of the U-Ga layers increases with the ionic radius of the transition metal element T. The observed antiferromagnetic reflections can be well explained with the Nel-type structure for UNiGa, whereas UPtGa has the antiferromagnetic stacking of the ferromagnetically ordered uranium moments in the -plane. The orbital contributions in the magnetic form factor are reduced from the free ion value, especially for UNiGa. This suppression shows a strong correlation with the bulk magnetic susceptibility. The tetragonality of the U-Ga layers is a sensitive measure of the nearest neighbour interaction, the lattice anomaly, and the orbital contribution and suggests that orbital degrees of freedom may play an important role for the magnetic properties in these itinerant 5 antiferromagnets.
Ishii, Kenji; Fujiwara, Akihiko*; Suematsu, Hiroyoshi*; Kubozono, Yoshihiro*
Physical Review B, 65(13), p.134431_1 - 134431_6, 2002/03
We have studied crystal structure, magnetism and electric transport properties of a europium fulleride EuC and its Sr-substituted compounds, EuSrC. They have a structure, which is an isostructure of other C ( represents an alkali atom or an alkaline earth atom). Magnetic measurements revealed that magnetic moment is ascribed to the divalent europium atom with = 7/2 spin, and a ferromagnetic transition was observed at = 10 - 14 K. In EuC, we also confirm the ferromagnetic transition by heat capacity measurement. The striking feature in EuSrC is very large negative magnetoresistance at low temperature; the resistivity ratio ( = 9 T)/( = 0 T) reaches almost 10 at 1 K in EuC. Such large magnetoresistance is the manifestation of a strong - interaction between conduction carriers on C and 4 electrons of Eu.
Kawarazaki, Shuzo*; Sato, Masugu*; Miyako, Yoshihito*; Chigusa, Nobusato*; Watanabe, Kenji*; Metoki, Naoto; Koike, Yoshihiro; Nishi, Masakazu*
Physical Review B, 61(6), p.4167 - 4173, 2000/02
no abstracts in English