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Journal Articles

Field-induced incommensurate-to-commensurate transition in the triangular lattice antiferromagnet GdPd$$_2$$Al$$_3$$

Inami, Toshiya; Terada, Noriki*; Kitazawa, Hideaki*; Sakai, Osamu*

Journal of Physics; Conference Series, 200, p.032022_1 - 032022_4, 2010/02

 Times Cited Count:0 Percentile:0.04

Journal Articles

Partial order of frustrated Potts model

Igarashi, Ryo; Ogata, Masao*

Journal of Physics; Conference Series, 200, p.022019_1 - 022019_4, 2010/02

 Times Cited Count:1 Percentile:49.66

Journal Articles

Anisotropic transport properties of NpPd$$_5$$Al$$_2$$

Matsuda, Tatsuma; Haga, Yoshinori; Aoki, Dai*; Homma, Yoshiya*; Tateiwa, Naoyuki; Yamamoto, Etsuji; Onuki, Yoshichika

Journal of Physics; Conference Series, 200, p.012113_1 - 012113_4, 2010/02

 Times Cited Count:2 Percentile:67.92

The anisotropic superconductor NpPd$$_5$$Al$$_2$$ with ZrNi$$_2$$Al$$_5$$-type tetragonal structure was studied by means of electrical resistivity and Hall effect in the normal state. The temperature dependence of electrical resistivity $$rho(T)$$ shows a large anisotropic behavior. The resistivity for $$J|$$[001] is larger than that for $$J|$$[100] in the whole temperature region. At high temperatures $$rho(T)$$ is proportional to $$-log T$$, which is characteristic behavior in Kondo effect. The field dependence of Hall resistivity $$rho_{rm H}$$ shows a linear dependence up to 55 kOe with a large slope for the field. The slope of $$rho_{rm H}$$ for field along $$c$$-axis is negative, but for field along $$a$$-axis, the slope dramatically changed from negative to positive with increasing temperature.

Journal Articles

Magnetic transitions in YbCo$$_2$$Si$$_2$$

Kaneko, Koji; Stockert, O.*; Mufti, N.*; Kiefer, K.*; Klingner, C.*; Krellner, C.*; Geibel, C.*; Steglich, F.*

Journal of Physics; Conference Series, 200, p.032031_1 - 032031_4, 2010/02

 Times Cited Count:5 Percentile:86.91

Journal Articles

Quantum criticality in a uranium heavy fermion system revealed with NMR spin-spin relaxation

Kambe, Shinsaku; Sakai, Hironori; Tokunaga, Yo; Matsuda, Tatsuma; Haga, Yoshinori; Yasuoka, Hiroshi; Chudo, Hiroyuki; Walstedt, R. E.*

Journal of Physics; Conference Series, 200, p.012076_1 - 012076_4, 2010/02

 Times Cited Count:1 Percentile:49.66

In order to clarify quantum criticality in heavy fermion systems, we propose to use the Gaussian spin-echo decay rate $$1/T_{2G}$$ of the NMR spin-spin relaxation. In contrast to the spin-lattice relaxation rate $$1/T_1$$, which is connected with the dynamical susceptibility Im$$chi(q,omega)$$, $$1/T_{2G}$$ is driven by the static susceptibility Re$$chi(q,0)$$ at finite $$q$$ for an antiferromagnet. The combined quantity $$T_1T/T_{2G}^2$$ is found to provide key information in determining the nature of quantum criticality. The $$T$$-dependence of $$T_1T/T_{2G}^2$$ for the Sn site in the heavy fermion compound USn$$_3$$ is presented as an example.

Journal Articles

Magnetization process of the S=1/2 distorted diamond spin chain with the Dzyaloshinsky-Moriya interaction

Sakai, Toru; Okamoto, Kiyomi*; Tonegawa, Takashi*

Journal of Physics; Conference Series, 200, p.022052_1 - 022052_4, 2010/02

 Times Cited Count:4 Percentile:83.16

The distorted diamond chain has attracted a lot of interest, since the compound Cu$$_3$$(CO$$_3$$)$$_2$$(OH)$$_2$$, so-called azurite, was revealed to be a good candidate for this system. Although several theoretical studies were performed, the strong anisotropy observed in the magnetization measurement of azurite has not been explained very well. To solve the mechanism of this anisotropy, we introduce the Dzyaloshinsky-Moriya (DM) interaction suitable for the crystal symmetry of azurite. The numerical diagonalization study on this realistic model indicates that the anisotropy in the experimental magnetization curve would be reproduced with sufficiently large DM interaction.

Journal Articles

Charge-spin-orbital dynamics of one-dimensional two-orbital Hubbard model

Onishi, Hiroaki

Journal of Physics; Conference Series, 200, p.012152_1 - 012152_4, 2010/02

 Times Cited Count:2 Percentile:67.92

Journal Articles

Electronic states of magnetic refrigerator materials Mn$$_{0.9}$$Fe$$_{1.1}$$P$$_{0.55}$$As$$_{0.45}$$ using soft X-ray magnetic circular dichroism

Takeda, Yukiharu; Okane, Tetsuo; Okochi, Takuo*; Fujimori, Shinichi; Saito, Yuji; Yamagami, Hiroshi; Yabuta, Hisato*; Takabatake, Toshiro*

Journal of Physics; Conference Series, 200, p.012199_1 - 012199_4, 2010/02

 Times Cited Count:2 Percentile:67.92

no abstracts in English

Journal Articles

Magneto-electric effect in charge-ordered LuFe$$_{2}$$O$$_{4}$$

Kambe, Takashi*; Komatsu, Takuma*; Michiuchi, Takamasa*; Hayakawa, Hiroki*; Oishi, Daisuke*; Hanasaki, Noriaki*; Yoshii, Kenji; Ikeda, Naoshi*

Journal of Physics; Conference Series, 200, p.012077_1 - 012077_4, 2010/02

 Times Cited Count:4 Percentile:83.16

A magneto-electric effect (ME) was observed in a charge-ordered ferroelectric LuFe$$_{2}$$O$$_{4}$$. The dielectric response in a three-dimensional charge-ordered phase is strongly influenced by magnetic field, especially around the ferri-magnetic ordering temperature. We also show the relation between the oxygen stoichiometry and the ME signal character above the magnetic transition temperature.

Journal Articles

Doping effect on charge ordered structure in RFe$$_{2}$$O$$_{4}$$(R=Lu and Yb)

Matsuo, Yoji*; Mori, Shigeo*; Hirata, Akihiko*; Yoshii, Kenji; Ikeda, Naoshi*

Journal of Physics; Conference Series, 200, p.012128_1 - 012128_4, 2010/02

 Times Cited Count:3 Percentile:77.33

RFe$$_{2}$$O$$_{4}$$ (R= Ho-Lu,Y) is a novel ferroelectric material in which ferroelectric polarization is caused by the charge ordering (CO) of Fe$$^{2+}$$ and Fe$$^{3+}$$. In this work we investigated the CO structure and dielectric/magnetic properties in RFe$$_{2}$$O$$_{4}$$ and RFeCuO$$_{4}$$ (R=Lu,Yb, M=Cu,Co) by a transmission electron microscopy (TEM), combining with dielectric and magnetic measurements. LuFeCuO$$_{4}$$ is a dielectric compound, which shows the characteristic low-frequency dielectric dispersion. In addition, the Cu$$^{2+}$$ substitution in LuFe$$_{2}$$O$$_{4}$$ suppressed the formation of the CO structure and induced characteristic polar nanodomains with the 5-10nm size. Magnetic measurement revealed that LuFeCuO$$_{4}$$ shows the magnetic transition around 50K, which is much lower than the magnetictransition temperature of 250K in LuFe$$_{2}$$O$$_{4}$$. Our experimental results suggest that the polar nanodomains should be responsible for the magnetic/dielectric properties in RFeMO$$_{4}$$.

Journal Articles

Magnetic properties and ferromagnetic microstructures in Al-doped La$$_{1-x}$$Sr$$_{x}$$MnO$$_{3}$$

Mori, Shigeo*; Yoshidome, Kazuhiro*; Nagamine, Yuki*; Togawa, Yoshihiko*; Yoshii, Kenji; Takenaka, Koshi*

Journal of Physics; Conference Series, 200, p.012129_1 - 012129_4, 2010/02

 Times Cited Count:5 Percentile:86.91

Doping effect on ferromagnetic (FM) properties in perovskite manganites La$$_{1-x}$$Sr$$_{x}$$MnO$$_{3}$$ (x=0.175) were investigated by low-temperature Lorentz transmission electron microscopy (TEM), in combination with the conventional magnetic measurements. It is found that La$$_{0.825}$$Sr$$_{0.175}$$Mn$$_{0.95}$$Al$$_{0.05}$$O$$_{3}$$ exhibits a structural phase transition from the rhombohedral to orthorhombic structures at Ts$$sim$$116 K. During the rhombohedral-to-orthorhombic transition, the FM domain structures changed from the macroscopic FM domains to the FM ones with the wavy stripe pattern. The ac magnetic measurements also revealed that La$$_{0.825}$$Sr$$_{0.175}$$Mn$$_{0.95}$$Al$$_{0.05}$$O$$_{3}$$ shows unconventional magnetic behaviour at low temperature below 65 K. Partial substitution of non-magnetic Al$$^{3+}$$ for Mn$$^{3+}$$ has some influence on magnetic ordering and double-exchange interaction, which should induce insulator behaviour in the orthorhombic phase.

Journal Articles

Fe-doping effects on magnetism in hole-type superconductors of (Bi,Pb)$$_{2}$$Sr$$_{2}$$CuO$$_{6}$$

Hiraka, Haruhiro*; Wakimoto, Shuichi; Takeda, Masayasu; Kakurai, Kazuhisa; Matsumura, Daiju; Nishihata, Yasuo; Mizuki, Junichiro; Yamada, Kazuyoshi*

Journal of Physics; Conference Series, 200, p.012059_1 - 012059_4, 2010/02

 Times Cited Count:0 Percentile:0.04

We studied Fe-dopant effects on spin correlations in Bi$$_{1.75}$$Pb$$_{0.35}$$Sr$$_{1.90}$$CuO$$_{6+delta'}$$. Magnetic neutron elastic scattering, which is absent in a pristine sample, has been observed at incommensurate positions with an incommensurability of $$delta$$$$sim$$0.2. Surprisingly, this anomalously large $$delta$$ follows a linear relation $$delta$$$$sim$$$$p$$ even in the overdoped region, unlike for La$$_{2-x}$$Sr$$_{x}$$CuO$$_{4}$$. We discuss this specific feature observed in the overdoped phase from a dynamical stripe viewpoint.

Journal Articles

$$^{105}$$Pd NQR study on NpPd$$_5$$Al$$_2$$ and CePd$$_5$$Al$$_2$$

Chudo, Hiroyuki; Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Aoki, Dai*; Haga, Yoshinori; Matsuda, Tatsuma; Homma, Yoshiya*; Nakano, Yasunori*; Honda, Fuminori*; et al.

Journal of Physics; Conference Series, 200, p.012020_1 - 012020_4, 2010/02

 Times Cited Count:3 Percentile:77.33

We report the results of $$^{105}$$Pd NQR experiments on NpPd$$_5$$Al$$_2$$ and CePd$$_5$$Al$$_2$$. In the normal state at 6 K, the $$^{105}$$Pd NQR spectrum consists of four lines in both systems. These lines can be assigned to two sets of $$pm1/2leftrightarrowpm3/2$$ and $$pm3/2leftrightarrowpm5/2$$ NQR transitions arising from two crystallographically in equivalent Pd sites. From the analysis of the $$^{105}$$Pd NQR spectrum the nuclear quadrupole frequency $$nu_Q$$, asymmetry parameter $$eta$$ and electric field gradient $$V_{zz}$$ have been deduced.

Oral presentation

Single-channel vs multi-channel Kondo effects; SmTe and TmTe studied via resonant inelastic X-ray scattering under high pressure

Jarrige, I.; Rueff, J.-P.*; Shieh, S.*; Taguchi, Munetaka*; Oishi, Yasuo*; Matsumura, Takeshi*; Ishii, Hirofumi*; Hiraoka, Nozomu*; Cai, Y. Q.*

no journal, , 

Oral presentation

Intermediate-valence state in binary Cd-Yb quasicrystal and its crystalline approximant

Kawana, Daichi; Watanuki, Tetsu; Machida, Akihiko; Shobu, Takahisa; Aoki, Katsutoshi; Tsai, A. P.*

no journal, , 

no abstracts in English

Oral presentation

Electronic structure of UN; Angle resolved photoelectron spectroscopy study

Fujimori, Shinichi; Okochi, Takuo*; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi; Yamagami, Hiroshi; Aoki, Dai*; Yamamoto, Etsuji; Onuki, Yoshichika; Haga, Yoshinori

no journal, , 

Uranium nitride (UN) is a type I antiferromagnet with N$'e$el temperature $$T_{rm N}$$=53 K. Since U-U distance in this compound (3.46 ${AA}$) is close to the Hill limit (3.4 ${AA}$), nature of U 5$$f$$ electrons has been debated so far between localized and itinerant states. Recently, it has been suggested that the U 5$$f$$ electrons in this compound have dual (itinerant and localized) characters. We have studied Fermi surface and band structure of single crystal UN by angle resolved photoelectron spectroscopy (ARPES) to understand the nature of U 5$$f$$ states. In contrast to the previous ARPES results, quasi-particle bands originated from U 5$$f$$states were clearly observed in the present ARPES spectra. The obtained Fermi surface as well as band structure were well explained by the band structure calculation treating all U 5$$f$$ electrons as being itinerant. We have found that U 5$$f$$ electrons in this compound are very itinerant, and the antifferomagnetism in this compound is an itinerant origin.

Oral presentation

Small-angle neutron scattering study of sintered Nd-Fe-$$^{11}$$B magnets with different coercivity values

Akiya, Takahiro*; Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Kato, Hiroaki*

no journal, , 

In spite of tremendous efforts, a role of intergranular Nd-rich phase in sintered Nd-Fe-B magnets on the coercivity ($$H_{c}$$) seems to be still unclear. The purpose of this work is to perform small-angle neutron scattering experiments on the sintered Nd-Fe-$$^{11}$$B magnets with different $$H_{c}$$ values and to investigate whether there exists any correlation between the average structure and the magnitude of $$H_{c}$$. We found that the value of characterized intensity $$I(0)$$ did not depend on the $$H_{c}$$ when $$vec{q}$$ is parallel to the $$c$$-axis of the main Nd$$_{2}$$Fe$$_{14}$$B grain. On the other hand, for the $$vec{q} perp c{rm -axis}$$ configuration, we found that log $$I(0)$$ linearly increases with increasing $$H_{c}$$, for five different samples with $$H_{c}$$ ranging from 13 to 16 kOe owing to different annealing conditions.

Oral presentation

Smectic to nematic transition of magnetic texture in conical state of FeCoSi under an external magnetic field

Takeda, Masayasu; Endo, Yasuo; Onose, Yoshinori*; Kakurai, Kazuhisa; Suzuki, Junichi; Tokura, Yoshinori*

no journal, , 

Complex phase transition of magnetic long range order in Fe$$_{0.7}$$Co$$_{0.3}$$Si has been investigated by small-angle neutron scattering (SANS) measurements. We found liquidcrystal-like behavior of the magnetic textures under external magnetic fields. A variety of the scattering patterns, ring, crescent-shape, diffusive spots etc. appeared by changing temperatures and applying magnetic fields. This behavior can be explained by an analogy of the phase transition of the liquid crystal when the net magnetization of the conical state under the magnetic fields is regarded as the director of the liquid crystals.

Oral presentation

Study of electronic states of uranium chalcogenides using soft X-ray photoemission spectroscopy and magnetic circular dichroism

Takeda, Yukiharu; Okane, Tetsuo; Okochi, Takuo*; Fujimori, Shinichi; Saito, Yuji; Yamagami, Hiroshi; Fujimori, Atsushi*; Ikeda, Shugo*; Sakai, Hironori; Haga, Yoshinori; et al.

no journal, , 

no abstracts in English

Oral presentation

O Ka emission spectra of ilmenites MTiO$$_{3}$$ (M=Mn, Fe, Co and Ni)

Agui, Akane; Mizumaki, Masaichiro*

no journal, , 

no abstracts in English

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