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Journal Articles

Ferromagnetic crossover within the ferromagnetic order of U$$_{7}$$Te$$_{12}$$

Opletal, P.; Sakai, Hironori; Haga, Yoshinori; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Kambe, Shinsaku; Tokunaga, Yo

Journal of the Physical Society of Japan, 92(3), p.034704_1 - 034704_5, 2023/03

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

We investigate the physical properties of a single crystal of uranium telluride U$$_{7}$$Te$$_{12}$$. We have confirmed that U$$_{7}$$Te$$_{12}$$ crystallizes in the hexagonal structure with three nonequivalent crystallographic uranium sites. The paramagnetic moments are estimated to be approximately 1 $$mu_{B}$$ per the uranium site, assuming a uniform moment on all the sites. A ferromagnetic phase transition occurs at $$T_{rm C}$$= 48 K, where the in-plane magnetization increases sharply, whereas the out of-plane component does not increase significantly. With decreasing temperature further below $$T_{rm C}$$ under field-cooling conditions, the out-of-plane component increases rapidly around T$$^{star}$$= 26 K. In contrast, the in-plane component hardly changes at T$$^{star}$$. Specific heat measurement indicates no $$lambda$$-type anomaly around T$$^{star}$$, so this is a cross-over suggesting a reorientation of the ordering moments or successive magnetic ordering on the part of the multiple uranium sites.

Journal Articles

Magnetic Bragg peak enhancement under ultrasound injection

Shamoto, Shinichi*; Akatsu, Mitsuhiro*; Matsuura, Masato*; Kawamura, Seiko; Harii, Kazuya*; Ono, Masao*; Chang, L.-J.*; Ito, Takashi; Nemoto, Yuichi*; Ieda, Junichi

Physical Review Research (Internet), 4(1), p.013245_1 - 013245_7, 2022/03

Ultrasound injection effect on a magnetic Bragg peak of yttrium iron garnet has been studied by quasielastic neutron scattering. The magnetic Bragg peak is vastly enhanced with decreasing temperature. The energy width increases proportionally to the square root of the sample temperature increase induced by the ultrasound injection. Because the magnetic Bragg peak is enhanced by the lattice vibration, the enhancement is expected to relate to the spin-lattice coupling closely. An observed sharp drop above 100 K in the longitudinal mode suggests the degradation of the spin-lattice coupling. It is consistent with the decline of spin Seebeck effect with increasing temperature above 100 K, proving the degradation mechanism by the spin-lattice coupling.

Journal Articles

Observation of longitudinal magnetic fluctuations at a first-order ferromagnetic quantum phase transition in UGe$$_2$$

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

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

Journal Articles

Nonmagnetic-magnetic transition and magnetically ordered structure in SmS

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

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

Journal Articles

Intriguing behavior of UCo$$_{1-x}$$Rh$$_x$$Ge ferromagnets in magnetic field along the $$b$$ axis

Posp$'i$$v{s}$il, J.*; Haga, Yoshinori; Miyake, Atsushi*; Kambe, Shinsaku; Tokunaga, Yo; Tokunaga, Masashi*; Yamamoto, Etsuji; Proschek, P.*; Voln$'y$, J.*; Sechovsk$'y$, V.*

Physical Review B, 102(2), p.024442_1 - 024442_13, 2020/07

 Times Cited Count:5 Percentile:36.02(Materials Science, Multidisciplinary)

Journal Articles

Structural characterization and magnetic behavior of uranium compound U$$_2$$Pt$$_6$$Al$$_{15}$$

Haga, Yoshinori; Sugai, Takashi*; Matsumoto, Yuji*; Yamamoto, Etsuji

JPS Conference Proceedings (Internet), 29, p.013003_1 - 013003_5, 2020/02

Journal Articles

Magnetization study on the Ising ferromagnet URhGe with high-precision angle-resolved magnetic field near the hard axis

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

Journal Articles

Crystal structure and magnetic properties of new ternary uranium compound U$$_3$$TiBi$$_9$$

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

Journal Articles

Electronic states in EuCu$$_2$$(Ge$$_{1-x}$$Si$$_x$$)$$_2$$ based on the doniach phase diagram

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

 Times Cited Count:18 Percentile:76.73(Physics, Multidisciplinary)

Journal Articles

Anisotropic magnetic fluctuations in ferromagnetic superconductor UGe$$_2$$; $$^{73}$$Ge-NQR study at ambient pressure

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

 Times Cited Count:4 Percentile:37.16(Physics, Multidisciplinary)

Journal Articles

Experimental observation of temperature and magnetic-field evolution of the 4${it f}$ states in CeFe$$_{2}$$ revealed by soft X-ray magnetic circular dichroism

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


 Times Cited Count:2 Percentile:11.95(Materials Science, Multidisciplinary)

We revisit the delocalized character of the 4$$f$$ states of CeFe$$_2$$ 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 $$M_{4,5}$$ 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 $$M_{4,5}$$ XAS as well as the Fe $$L_{2,3}$$ XAS and XMCD. This unusual behavior is characterized by the $$J=7/2$$ states in a 4$$f^1$$ configuration mixed into the $$J=5/2$$ ground state. Such extreme sensitivity of the Ce 4$$f$$ states to the external perturbations can be related to the magnetic instability toward an antiferromagnetic phase in CeFe$$_2$$. Our experimental data presented here provide valuable insights into the underlying physics in strongly-hybridized ferromagnetic Ce compounds.

Journal Articles

Effect of pressure on magnetism of UIrGe

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

 Times Cited Count:9 Percentile:57.96(Physics, Multidisciplinary)

Journal Articles

Electronic structures of ferromagnetic CeAgSb$$_{2}$$; Soft X-ray absorption, magnetic circular dichroism, and angle-resolved photoemission spectroscopies

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

 Times Cited Count:13 Percentile:65.3(Physics, Multidisciplinary)

We report on the electronic structures of ferromagnetic CeAgSb$$_{2}$$ using soft X-ray absorption (XAS), magnetic circular dichroism (XMCD), and angle-resolved photoemission (ARPES) spectroscopies. The Ce $$M_{4,5}$$ XAS spectra show very small satellite structures, reflecting a strongly localized character of the Ce 4${it f}$ electrons. The linear dichroism effects in the Ce $$M_{4,5}$$ XAS spectra demonstrate the ground-state Ce 4${it f}$ symmetry of $$Gamma$$$$_{6}$$, the spatial distribution of which is directed along the ${it c}$-axis. Nevertheless, ARPES spectra at the Ce 3$$d$$-4$$f$$ resonance show the momentum dependence of the intensity ratio between Ce 4$$f^{1}_{5/2}$$ and 4$$f^{1}_{7/2}$$ peaks in a part of the Brillouin zone, suggesting the non negligible momentum-dependent hybridization effect between the Ce 4${it f}$ and the conduction electrons. This is associated with the moderate mass enhancement in CeAgSb$$_{2}$$.

Journal Articles

Single crystal growth of the plutonium-based superconductor PuRhGa$$_5$$ and anistropic superconducting properties

Haga, Yoshinori; Sakai, Hironori; Matsuda, Tatsuma; Tokunaga, Yo; Fujimoto, Tatsuya; Kambe, Shinsaku; Yamamoto, Etsuji; Nakamura, Akio; Walstedt, R. E.; Yasuoka, Hiroshi; et al.

Kotai Butsuri, 40(7), p.519 - 526, 2005/07

Single crystals of the plutonium-based superconductor PuRhGa$$_5$$ have been successufully grown. The anisotropic superconducting properties were investigated by magnetization and Ga-NQR measurements. Large anisotropy of the upper critical field and the presence of line nodes on the Fermi surface were revealed, indicating the quasi-two-dimensional electronic state as well as the magnetically mediated superconductivity.

Journal Articles

Electrical and magnetic properties of a single crystal UCu$$_2$$Si$$_2$$

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

 Times Cited Count:23 Percentile:72.34(Physics, Multidisciplinary)

We have succeeded in growing a high-quality single crystal of UCu$$_2$$Si$$_2$$ with the tetragonal structure by the Sn-flux method and measured the electrical resistivity, magnetic susceptibility, magnetization and specific heat. UCu$$_2$$Si$$_2$$ is found to order antiferromagnetically below $$T_{rm N}$$ = 106 K, and follows a successive ferromagnetic ordering at $$T_{rm C}$$ = 100 K. The magnetic properties are highly anisotropic, reflecting the crystal structure. An easy-axis of magnetization is found to be the [001] direction ($$c$$-axis) both in the antiferromagnetic and ferromagnetic phases, while the [100] direction ($$a$$-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 $$T_{rm C}$$ = 100 K. The saturation moment is determined as 1.75$$mu_{rm B}$$/U at 2 K. The electronic specific heat coefficient is also determined as 20 mJ/K$$^2$$$$cdot$$mol.

Journal Articles

X-ray magnetic circular dichroism at the U $$N_{4,5}$$ edges of uranium monochalcogenides US, USe and UTe

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

 Times Cited Count:6 Percentile:34.21(Physics, Condensed Matter)

Magnetic circular dichroism (MCD) has been measured at the U $$N_{4,5}$$ 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.

Journal Articles

Large orbital magnetic moment and its quenching in the itinerant uranium intermetallic compounds U${it T}$Ga$$_5$$ (${it T}$=Ni, Pd, Pt)

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

 Times Cited Count:59 Percentile:88.9(Materials Science, Multidisciplinary)

The crystal structure, lattice strain due to the antiferromagnetic ordering and magnetic form factor in the itinerant 5$$f$$ compounds UTGa$$_5$$ (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 N$'e$el-type structure for UNiGa$$_5$$, whereas UPtGa$$_5$$ has the antiferromagnetic stacking of the ferromagnetically ordered uranium moments in the $$c$$-plane. The orbital contributions in the magnetic form factor are reduced from the free ion value, especially for UNiGa$$_5$$. 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$$f$$ antiferromagnets.

JAEA Reports

Abstracts of the Workshop on Orbital Ordering and Fluctuations in d- and f-electron Systems; March 4-6, 2002, ASRC, JAERI, Tokai, Japan

Ueda, Kazuo; Hotta, Takashi

JAERI-Review 2002-037, 31 Pages, 2002/12


Strongly correlated f- and d-electron systems including heavy Fermion systems and transition metal oxides are important source of exciting new phenomena in condensed matter physics. Recently it has been recognized in more profound way that the orbital degeneracy of the f- and d-electrons plays very important role underlying those exotic phenomena. The idea of the present workshop is to bring active researchers in the field together and to exchange ideas in informal atmosphere. In the workshop many interesting results were presented and stimulating discussions were made as clearly seen by the present report.

Journal Articles

Ferromagnetism and giant magnetoresistance in the rare-earth fullerides Eu$$_{6-x}$$Sr$$_x$$C$$_{60}$$

Ishii, Kenji; Fujiwara, Akihiko*; Suematsu, Hiroyoshi*; Kubozono, Yoshihiro*

Physical Review B, 65(13), p.134431_1 - 134431_6, 2002/03

 Times Cited Count:32 Percentile:78.34(Materials Science, Multidisciplinary)

We have studied crystal structure, magnetism and electric transport properties of a europium fulleride Eu$$_6$$C$$_{60}$$ and its Sr-substituted compounds, Eu$$_{6-x}$$Sr$$_x$$C$$_{60}$$. They have a $$bcc$$ structure, which is an isostructure of other $$M_6$$C$$_{60}$$ ($$M$$ represents an alkali atom or an alkaline earth atom). Magnetic measurements revealed that magnetic moment is ascribed to the divalent europium atom with $$S$$ = 7/2 spin, and a ferromagnetic transition was observed at $$T_C$$ = 10 - 14 K. In Eu$$_6$$C$$_{60}$$, we also confirm the ferromagnetic transition by heat capacity measurement. The striking feature in Eu$$_{6-x}$$Sr$$_x$$C$$_{60}$$ is very large negative magnetoresistance at low temperature; the resistivity ratio $$rho$$($$H$$ = 9 T)/$$rho$$($$H$$ = 0 T) reaches almost 10$$^{-3}$$ at 1 K in Eu$$_6$$C$$_{60}$$. Such large magnetoresistance is the manifestation of a strong $$pi$$-$$f$$ interaction between conduction carriers on C$$_{60}$$ and 4$$f$$ electrons of Eu.

Journal Articles

Ground-state magnetic structure of CeRh$$_{2}$$Si$$_{2}$$ and response to hydrostatic pressure as studied by neutron diffraction

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

 Times Cited Count:84 Percentile:93.59(Materials Science, Multidisciplinary)

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38 (Records 1-20 displayed on this page)