Rattling-Induced Superconductiviy in the Beta-Pyrochlore Oxides AOs2O6 (2009)
Nagao, Yohei, Yamaura, Jun-ichi, Ogusu, Hiroki, Okamoto, Yoshihiko, Hiroi, Zenji
The superconducting properties of two beta-pyrochlore oxides, CsOs2O6 and RbOs2O6, are studied by thermodynamic and transport measurements using high-quality single crystals. It is shown that the...
Magnetization "Steps" on a Kagome Lattice in Volborthite (2009)
Yoshida, Hiroyuki, Okamoto, Yoshihiko, Tayama, Takashi, Sakakibara, Toshiro, Tokunaga, Masashi, Matsuo, Akira, ...
Magnetic properties of the spin-1/2 kagome-like compound volborthite are studied using a high-quality polycrystalline sample. It is evidenced from magnetization and specific heat measurements that...
Vesignieite BaCu3V2O8(OH)2 as a Candidate Spin-1/2 Kagome Antiferromagnet (2009)
Okamoto, Yoshihiko, Yoshida, Hiroyuki, Hiroi, Zenji
A polycrystalline sample of vesignieite BaCu3V2O8(OH)2 comprising a nearly ideal kagome lattice composed of Cu2+ ions carrying spin 1/2 has been synthesized and studied by magnetization and heat...
Okamoto, Yoshihiko, Niitaka, Seiji, Uchida, Masaya, Waki, Takeshi, Takigawa, Masashi, Nakatsu, Yoshitaka, ...
We have synthesized a new spinel oxide LiRh2O4 with a mixed-valent configuration of Rh3+ and Rh4+. At room temperature it is a paramagnetic metal, but on cooling, a metal-insulator transition occurs...
Unique Phase Transition on Spin-2 Triangular Lattice of Ag2MnO2 (2008)
Yoshida, Hiroyuki, Ahlert, Sascha, Jansen, Martin, Okamoto, Yoshihiko, Yamaura, Jun-Ichi, Hiroi, Zenji
Ag2MnO2 is studied as a possible candidate compound for an antiferromagnetic XY spin model on a triangular lattice. In spite of the large Curie-Weiss temperature of -430 K found in magnetic...
Spin-Liquid State in the S = 1/2 Hyperkagome Antiferromagnet Na4Ir3O8 (2007)
Okamoto, Yoshihiko, Nohara, Minoru, Aruga-Katori, Hiroko, Takagi, Hidenori
A spinel related oxide, Na4Ir3O8, was found to have a three dimensional network of corner shared Ir4+ (t2g^5) triangles. This gives rise to an antiferromagnetically coupled S = 1/2 spin system formed...
Precise Control of Band Filling in NaxCoO2 (2007)
Yoshizumi, Daisuke, Muraoka, Yuji, Okamoto, Yoshihiko, Kiuchi, Yoko, Yamaura, Jun-Ichi, Mochizuki, Masahito, ...
Electronic properties of the sodium cobaltate NaxCoO2 are systematically studied through a precise control of band filling. Resistivity, magnetic susceptibility and specific heat measurements are...
Metal-insulator Transition in a Pyrochlore-type Ruthenium oxide, Hg2Ru2O7 (2007)
Yamamoto, Ayako, Sharma, Peter A., Okamoto, Yoshihiko, Nakao, Aiko, Katori, Hiroko Aruga, Niitaka, Seiji, ...
A new pyrochlore ruthenium oxide, Hg2Ru2O7 was synthesized under a high pressure of 6 GPa. In contrast to the extensively studied Ru4+ oxides, this compound possesses a novel Ru5+ valence state,...