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Journal Articles

Devil's staircase transition of the electronic structures in CeSb

Kuroda, Kenta*; Arai, Yosuke*; Rezaei, N.*; Kunisada, So*; Sakuragi, Shunsuke*; Alaei, M.*; Kinoshita, Yuto*; Bareille, C.*; Noguchi, Ryo*; Nakayama, Mitsuhiro*; et al.

Nature Communications (Internet), 11, p.2888_1 - 2888_9, 2020/06

 Times Cited Count:1 Percentile:55.66(Multidisciplinary Sciences)

Journal Articles

The $$f$$-electron state of the heavy fermion superconductor NpPd$$_5$$Al$$_2$$ and the isostructural family

Metoki, Naoto; Aczel, A. A.*; Aoki, Dai*; Chi, S.*; Fernandez-Baca, J. A.*; Griveau, J.-C.*; Hagihala, Masato*; Hong, T.*; Haga, Yoshinori; Ikeuchi, Kazuhiko*; et al.

JPS Conference Proceedings (Internet), 30, p.011123_1 - 011123_6, 2020/03

Rare earths (4$$f$$) and actinides (5$$f$$) provide variety of interesting states realized with competing interactions between the increasing number of $$f$$ electrons. Since crystal field splitting of many-body $$f$$ electron system is smaller than the bandwidth, (1) high resolution experiments are needed, (2) essentially no clear spectrum with well defined peaks is expected in itinerant Ce and U compounds, and (3) Np and Pu is strictly regulated. Therefore, systematic research on magnetic excitations by neutron scattering experiments of localized compounds and rare earth iso-structural reference is useful. We describe the $$f$$ electron states of heavy electron compounds NpPd$$_5$$Al$$_2$$ and actinide and rare earth based iso-structural family.

Journal Articles

$$f$$-electron states in PrPd$$_5$$Al$$_2$$

Metoki, Naoto; Yamauchi, Hiroki; Suzuki, Hiroyuki*; Kitazawa, Hideaki*; Hagihala, Masato*; Masuda, Takatsugu*; Aczel, A. A.*; Chi, S.*; Hong, T.*; Matsuda, Masaaki*; et al.

Journal of the Physical Society of Japan, 87(9), p.094704_1 - 094704_8, 2018/09

 Times Cited Count:5 Percentile:40.64(Physics, Multidisciplinary)

The $$f$$-electron states of PrPd$$_5$$Al$$_2$$ were revealed by neutron inelastic scattering. The flat $$f$$-orbitals with large $$J_z$$ become stable under the two-dimensional CEF potential of unique crystal structure, which is the origin of the Ising anisotropy. A systematic understanding is possible in RPd$$_5$$Al$$_2$$ based on this CEF potential. Especially the $$XY$$-type anisotropy in NpPd$$_5$$Al$$_2$$ can be qualitatively understood with the positive Stevens factors. It mean that the local property is important for the physical properties of RPd$$_5$$Al$$_2$$ including the heavy fermion superconductivity in NpPd$$_5$$Al$$_2$$.

Journal Articles

Neutron inelastic scattering study of the $$f$$-electron states in NdPd$$_5$$Al$$_2$$

Metoki, Naoto; Yamauchi, Hiroki; Suzuki, Hiroyuki*; Kitazawa, Hideaki*; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro

Journal of the Physical Society of Japan, 87(8), p.084708_1 - 084708_7, 2018/08

 Times Cited Count:5 Percentile:40.64(Physics, Multidisciplinary)

Inelastic neutron scattering experiments were carried out in order to study the $$f$$-electron states of NdPd$$_5$$Al$$_2$$The CEF levels at 0K, 35.4K, 88.3K, 101.5K, and 198.8K were clarified from the excitation spectra. The $$Gamma_6$$ ground state contains the orbital with $$J_z=pm9/2$$ as a main component due to a large negative B$$_{20}=-1.4$$K, which is the origin of the strong uniaxial anisotropy. The estimated magnetic moment, the calculated susceptibility, magnetization curve, and specific heat are in good agreement with the experimental data. The existence of a common charge distribution with CePd$$_5$$Al$$_2$$ and PrPd$$_5$$Al$$_2$$. Indicates that a localized character is important even in actinide-based iso-structural compounds as actually observed in UPd$$_5$$Al$$_2$$ and also NpPd$$_5$$Al$$_2$$, in which the valence crossover plays important role for the heavy fermion superconductivity.

Journal Articles

Experimental determination of the topological phase diagram in Cerium monopnictides

Kuroda, Kenta*; Ochi, Masayuki*; Suzuki, Hiroyuki*; Hirayama, Motoaki*; Nakayama, Mitsuhiro*; Noguchi, Ryo*; Bareille, C.*; Akebi, Shuntaro*; Kunisada, So*; Muro, Takayuki*; et al.

Physical Review Letters, 120(8), p.086402_1 - 086402_6, 2018/02

 Times Cited Count:20 Percentile:10.42(Physics, Multidisciplinary)

Journal Articles

Neutron powder diffraction study on the magnetic structure of NdPd$$_5$$Al$$_2$$

Metoki, Naoto; Yamauchi, Hiroki; Kitazawa, Hideaki*; Suzuki, Hiroyuki*; Hagihala, Masato*; Frontzek, M. D.*; Matsuda, Masaaki*; Fernandez-Baca, J. A.*

Journal of the Physical Society of Japan, 86(3), p.034710_1 - 034710_5, 2017/03

 Times Cited Count:8 Percentile:33.37(Physics, Multidisciplinary)

Magnetic structure of NdPd$$_5$$Al$$_2$$ has been studied by means of neutron powder diffraction. We observed remarkable magnetic reflections with the modulation vector $$q$$= (1/2 0 0) below the ordering temperature $$T_{rm N}$$ = 1.2 K. We found a collinear magnetic structure of Nd moment of 2.9(1) $${mu}_{rm B}$$ at 0.3 K parallel to the $$c$$-axis, where the ferromagnetically ordered $$a$$ planes stack with four Nd layer period of ++-- sequence along the $$a$$ direction with the distance between adjuscent Nd layers to be $$a/2$$. This is very similar to CePd$$_5$$Al$$_2$$ with $$q$$ = (0.23 0.23 0) and the Ce moment parallel to the $$c$$-axis. These structures with in-plane modulation $$q_{|}$$ is a consequence of the two dimensional nature of fermi surface topology in this family, coming from unique crystal structure with very long tetragonal unit cell and large distance $$>$$ 7${AA}$ between the rare earth layers separated by Al and two Pd layers.

Journal Articles

Magnetic ordering in pressure-induced phases with giant spin-driven ferroelectricity in multiferroic TbMnO$$_{3}$$

Terada, Noriki*; Khalyavin, D. D.*; Manuel, P.*; Osakabe, Toyotaka; Kikkawa, Akiko*; Kitazawa, Hideaki*

Physical Review B, 93(8), p.081104_1 - 081104_5, 2016/02

 Times Cited Count:16 Percentile:28.22(Materials Science, Multidisciplinary)

We performed neutron diffraction experiments under high pressures and high magnetic fields using a single crystal of the multiferroic compound TbMnO$$_{3}$$ in order to clarify the mechanism associated with pressure/magnetic-field-induced giant ferroelectric polarization. We found that the E-type ordering of Mn spins induces giant ferroelectric polarization over all the parameter regions investigated, through an exchange striction mechanism. Furthermore, we propose that the polarization is reduced by polar ordering of the Tb moments in a zero magnetic field and is enhanced via the field-induced transition from polar to nonpolar Tb orderings at 2T.

Journal Articles

Speciation of radioactive soil particles in the Fukushima contaminated area by IP autoradiography and microanalyses

Mukai, Hiroki*; Hatta, Tamao*; Kitazawa, Hideaki*; Yamada, Hirohisa*; Yaita, Tsuyoshi; Kogure, Toshihiro*

Environmental Science & Technology, 48(22), p.13053 - 13059, 2014/12

 Times Cited Count:87 Percentile:4.11(Engineering, Environmental)

no abstracts in English

Journal Articles

Pressure-induced polar phases in multiferroic delafossite CuFeO$$_{2}$$

Terada, Noriki*; Khalyavin, D. D.*; Manuel, P.*; Osakabe, Toyotaka; Radaelli, P. G.*; Kitazawa, Hideaki*

Physical Review B, 89(22), p.220403_1 - 220403_6, 2014/06

AA2014-0251.pdf:1.02MB

 Times Cited Count:28 Percentile:19.34(Materials Science, Multidisciplinary)

We have studied the pressure effect on the magnetic orderings in the strongly frustrated antiferromagnet CuFeO$$_{2}$$, by using neutron diffraction experiments under hydrostatic pressure. The main result is elucidation of the pressure-temperature magnetic phase diagram, consisting of the fourmagnetic phases including two polar ones. In particular, in the 3 GPa $$<$$ P $$<$$ 4 GPa pressure range, the ICM2 phase with the proper screw magnetic ordering stabilized. This polar phase is almost identical to the ferroelectric incommensurate (FEIC) phase induced by either a magnetic field or chemical doping. Furthermore, above 4 GPa, a new low-symmetry phase ICM3 is realized. This is unique for the family of delafossite multiferroics and implies an admixture of both cycloidal and proper screw spin configurations. The sequence of the observed magnetic phases with changing pressure might be attributed to pressure suppression of the monoclinic lattice distortions responsible for releasing the spin frustration in the system.

Journal Articles

Magnetic and nonmagnetic impurity effect on magnetic orderings of the isosceles-triangular-lattice antiferromagnet CuMnO$$_2$$

Terada, Noriki*; Tsuchiya, Yoshinori*; Kitazawa, Hideaki*; Metoki, Naoto

Journal of the Korean Physical Society, 62(12), p.1905 - 1909, 2013/06

 Times Cited Count:2 Percentile:77.19(Physics, Multidisciplinary)

We have investigated magnetic and nonmagnetic impurity substitution effects on magnetic ordering of a frustrated isosceles triangular lattice antiferromagnet CuMnO$$_2$$ by means of the magnetic neutron diffraction measurements on Cu(Mn$$_{1-y}$$Ga$$_y$$)O$$_2$$. While the magnetic wave vector of the magnetic ground state of "magnetically" substituted Cu(Mn$$_{1-x}$$Cu$$_x$$)O$$_2$$ with x = 0:04 is Q = (-1/2 1/2 0), that in the "nonmagnetically" substituted Cu(Mn$$_{1-y}$$Ga$$_y$$)O$$_2$$ with y =0.05, 0.15 and 0.20 is Q = (-1/2 1/2 1/2) that is identical to that of pure CuMnO$$_2$$. We discuss an influence of magnetic or nonmagnetic impurity substitution on the magnetic ordering of CuMnO$$_2$$, by comparing the results of Cu(Mn$$_{1-y}$$Ga$$_y$$)O$$_2$$ with Cu(Mn$$_{1-x}$$Cux)O$$_2$$.

Journal Articles

Uniaxial-pressure control of magnetic phase transitions in a frustrated magnet CuFe$$_{1-x}$$Ga$$_{x}$$O$$_{2}$$ (x =0, 0.018)

Nakajima, Taro*; Mitsuda, Setsuo*; Takahashi, Keiichiro*; Yoshitomi, Keisuke*; Masuda, Kazuya*; Kaneko, Chikafumi*; Homma, Yuki*; Kobayashi, Satoru*; Kitazawa, Hideaki*; Kosaka, Masashi*; et al.

Journal of the Physical Society of Japan, 81(9), p.094710_1 - 094710_8, 2012/09

Journal Articles

Uniaxial-pressure control of magnetic phase transitions in a frustrated magnet CuFe$$_{1-x}$$Ga$$_{x}$$O$$_{2}$$ ($$x$$ = 0, 0.018)

Nakajima, Taro*; Mitsuda, Setsuo*; Takahashi, Keiichiro*; Yoshitomi, Keisuke*; Masuda, Kazuya*; Kaneko, Chikafumi*; Homma, Yuki*; Kobayashi, Satoru*; Kitazawa, Hideaki*; Kosaka, Masashi*; et al.

Journal of the Physical Society of Japan, 81(9), p.094710_1 - 094710_8, 2012/09

 Times Cited Count:12 Percentile:36.34(Physics, Multidisciplinary)

Journal Articles

Conduction band caused by oxygen vacancies in aluminum oxide for resistance random access memory

Nigo, Seisuke*; Kubota, Masato; Harada, Yoshitomo*; Hirayama, Taisei*; Kato, Seiichi*; Kitazawa, Hideaki*; Kido, Giyu*

Journal of Applied Physics, 112(3), p.033711_1 - 033711_6, 2012/08

 Times Cited Count:51 Percentile:10.04(Physics, Applied)

Journal Articles

Neutron scattering studies of the spin-5/2 antiferromagnetic linear trimer substance SrMn$$_3$$P$$_4$$O$$_{14}$$

Hase, Masashi*; D$"o$nni, A.*; Ozawa, Kiyoshi*; Kitazawa, Hideaki*; Sakai, Osamu*; Pomjakushin, V. Y.*; Keller, L.*; Kaneko, Koji; Metoki, Naoto; Kakurai, Kazuhisa; et al.

Journal of Physics; Conference Series, 340, p.012066_1 - 012066_7, 2012/00

 Times Cited Count:1 Percentile:52.44

We determined the magnetic structure below $$T_{rm N1}=2.2(1)$$ K of the spin-5/2 antiferromagnetic (AF) trimer substance SrMn$$_3$$P$$_4$$O$$_{14}$$ using neutron powder diffraction experiments. The incommensurate propagation vector is expressed as [0, $$k_y$$, 0], due to competition between the nearest-neighbor and next-nearest-neighbor interactions in trimerized chains. The value of $$k_y$$ is 0.316 to 0.331, changing rapidly at $$T_{rm N2}= 1.75(5)$$ K. We confirmed that the intra-trimer $$J_1$$ interaction is AF. The magnetic excitation peaks were obsereved at 0.46, 0.68, and 1.02 meV. The weak Q dependence indicates the discrete energy levels, which do not contradict the AF trimer model with the intra-trimer interaction value of 0.29 meV (3.4 K).

Journal Articles

Magnetic excitations in the spin-5/2 antiferromagnetic trimer substance SrMn$$_3$$P$$_4$$O$$_{14}$$

Hase, Masashi*; Matsuda, Masaaki*; Kaneko, Koji; Metoki, Naoto; Kakurai, Kazuhisa; Yang, T.*; Cong, R.*; Lin, J.*; Ozawa, Kiyoshi*; Kitazawa, Hideaki*

Physical Review B, 84(21), p.214402_1 - 214402_6, 2011/12

 Times Cited Count:9 Percentile:56.74(Materials Science, Multidisciplinary)

Journal Articles

Magnetic correlations and the influence of atomic disorder in frustrated isosceles triangular lattice antiferromagnet CuMnO$$_2$$

Terada, Noriki*; Tsuchiya, Yoshinori*; Kitazawa, Hideaki*; Osakabe, Toyotaka; Metoki, Naoto; Igawa, Naoki; Oyama, Kenji*

Physical Review B, 84(6), p.064432_1 - 064432_8, 2011/08

 Times Cited Count:15 Percentile:41.41(Materials Science, Multidisciplinary)

We have studied the magnetic correlations of the isosceles triangular lattice antiferromagnet CuMnO$$_2$$. Above $$T$$$$_{rm N}$$, the magnetic correlations are characterized by a two-dimensional (2D) short-range correlation. Below $$T$$$$_{rm N}$$, the magnetic structures have been identified to be collinear with the magnetic moments almost parallel to the $$d_{z^2}$$ orbitals. The stacking sequence along the $$c$$ direction is changed from antiferromagnetic to ferromagnetic by atomic disorder. We find that the second-nearest-neighbor interlayer interaction plays an important role for the magnetic stacking along the $$c$$ axis. The magnetic excitation below $$T$$$$_{rm N}$$ is characterized by collective spin-wave excitation with an energy gap of 6 meV from the three-dimensional long-range magnetic order and by spin-liquid-like 2D excitation, indicated by specific heat.

Journal Articles

High-pressure suppression of long-range magnetic order in the triangular-lattice antiferromagnet CuFeO$$_{2}$$

Terada, Noriki*; Osakabe, Toyotaka; Kitazawa, Hideaki*

Physical Review B, 83(2), p.020403_1 - 020403_4, 2011/01

 Times Cited Count:10 Percentile:53.74(Materials Science, Multidisciplinary)

We succeeded in observing pressure-suppressed magnetic long-range ordering (LRO) in the triangular-lattice antiferromagnet CuFeO$$_{2}$$, using neutron-diffraction experiments under an isotropic pressure. The magnetic LRO of the four-sublattice ground state under ambient pressure in CuFeO$$_{2}$$ almost disappears at the high pressure of 7.9 GPa, and is replaced by an incommensurate order with temperature-independent wave number of (0.192 0.192 1.5). The incommensurate wave number observed at 7.9 GPa corresponds to that observed just above the temperature at which lattice distortion and magnetic LRO simultaneously occur under ambient pressure. Therefore, the long-range magnetic ordering disappears because the high pressure suppressed the lattice distortion that otherwise relieves spin frustration and leads the spin system to LRO.

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:100

Journal Articles

Exchange-striction associated with the elliptical proper helical magnetic structure in the ferroelectric phase of CuFe$$_{1-y}$$Ga$$_{y}$$O$$_{2}$$

Terada, Noriki*; Nakajima, Taro*; Mitsuda, Setsuo*; Matsuda, Masaaki; Kakurai, Kazuhisa; Tanaka, Yoshihito*; Kitazawa, Hideaki*

Journal of Physics; Conference Series, 211(1), p.012005_1 - 012005_6, 2010/01

 Times Cited Count:2 Percentile:29.85

Journal Articles

A New method for the quantitative analysis of the scale and composition of nanosized oxide in 9Cr-ODS steel

Onuma, Masato*; Suzuki, Junichi; Otsuka, Satoshi; Kim, S.-W.; Kaito, Takeji; Inoue, Masaki; Kitazawa, Hideaki*

Acta Materialia, 57(18), p.5571 - 5581, 2009/10

 Times Cited Count:98 Percentile:2.44(Materials Science, Multidisciplinary)

54 (Records 1-20 displayed on this page)