Faculty Profiles - TAKEDA Naoya

Papers - TAKEDA Naoya

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Coexistence of distinct Ce 4f-electron states at inequivalent crystallographic sites: CePtGe2 case

Hayato Muto, Tomohito Nakano, Tatsuya Watanabe, Ryota Takahashi, Naoya Takeda, Jun Gouchi, Yoshiya Uwatoko, Michal Dušek, Jan Prokleška, Jiří Pospíšil, Vladimír Sechovský

Journal of Magnetism and Magnetic Materials 613 172670 - 172670 2025.2

First-order transition under a magnetic ordered state in SmPtSi2

Tomohito Nakano, Eisuke Takahashi, Shuto Yamaguchi, Naoya Takeda, Klára Uhlířová, Jan Prokleška, Jiří Pospíšil, Vladimír Sechovský, Kazuyuki Matusbayashi, Hanming Ma, Yoshiya Uwatoko

Physica Scripta 99 ( 8 ) 085923 - 085923 2024.7

Publishing type：Research paper (scientific journal) Publisher：IOP Publishing

Abstract

We have synthesized polycrystalline and single-crystalline samples of SmPtSi2, and measured their resistivity, specific heat, magnetization, and Seebeck coefficient. The existence of two magnetic phase transitions has been confirmed, one at T H = 8.6 K and the other T L = 5.6 K. A hump-type anomaly in resistivity, a lambda-type anomaly in specific heat, a downward bend in magnetization, and a semiconductor-like increase in the Seebeck coefficient were observed at T H, indicating an antiferromagnetic transition accompanied by a gap opening on the Fermi surface. In contrast, a sharp drop in resistivity, a sharp spike in specific heat, and a drop in magnetization were observed at T L. The Seebeck coefficient showed metallic temperature dependence below T L. With increasing pressure, T H and T L shifted to higher temperatures. The transition at T L was no longer observed at pressures above 1.5 GPa. These findings suggest that the transition at T L is a transition from an antiferromagnetic ordered state with the gap on the Fermi surface to a different antiferromagnetic state.

DOI： 10.1088/1402-4896/ad59e0

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Other Link： https://iopscience.iop.org/article/10.1088/1402-4896/ad59e0/pdf

Y-Substitution Effects on Electrical Resistivity of (Ce1−yYy)PtGe2

Hayato Muto, Shoma Onuma, Tatsuya Watanabe, Ryota Takahashi, Tomohito Nakano, Naoya Takeda, Jun Gouchi, Yoshiya Uwatoko, Klára Uhlířová, Jan Prokleška, Vladimír Sechovský

Proceedings of the 29th International Conference on Low Temperature Physics (LT29) 2023.5

La-Substitution Effects on Multisite Ce Compound CePtGe<inf>2</inf>

Hayato Muto, Shoma Onuma, Tomohito Nakano, Naoya Takeda, Jun Gouchi, Yoshiya Uwatoko, Klára Uhlířová, Jan Prokleška, Vladimír Sechovský

Journal of the Physical Society of Japan 91 ( 7 ) 2022.7

Publishing type：Research paper (scientific journal)

The CePtGe2 compound, which shows antiferromagnetic transition at Néel temperature TN = 3.8 K, has two crystallographically inequivalent Ce sites. Recently, the coexistence of a localized f-electron state at one of two Ce sites and an itinerant heavy f-electron state at the other Ce site has been suggested. In this study, we have prepared polycrystalline samples of (Ce1-xLax)PtGe2 (x = 0 ∼ 0.2) and have measured their electrical resistivity and magnetization. The specific heat for x = 0.2 has been measured also. With increasing x, the downward bending of the temperature dependence of the resistivity and the cusp-type anomaly in the susceptibility associated with TN shift to lower temperatures with a linear extrapolation of TN directing to 0 K at x ∼ 0.5. Also, the saturation magnetization decreases linearly with increasing x, pointing to the disappearance of magnetic moments at the same La concentration. These results indicate that only the Ce ions with the localized f-electron are substituted by La ions. On the other hand, the transition from the antiferromagnetic state to the ferromagnetic-like polarized magnetic state at a very weak magnetic field, which is comparable to that of conventional Ferrite magnets, was realized via the La-substitution.

DOI： 10.7566/JPSJ.91.074712

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Superconductivity of the ternary stannide Y5Co6Sn18

Naoki Kase, Taishi Anada, Yusuke Terui, Tomohito Nakano, Naoya Takeda

PHYSICA B-CONDENSED MATTER 587 2020.6

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER

Superconductivity is newly discovered in a single crystal of Y5Co6Sn18 at superconducting transition temperature T-c = 0.7 K. The single crystals are grown by a Sn flux method. Superconducting and normal properties of Y5Co6Sn18 are investigated by means of electrical resistivity rho(T) and specific heat C(T) measurements. Superconductivity is of bulk nature because of the jump at T-c from specific heat measurements. The Sommerfeld constant gamma and Debye temperature Theta(D) are estimated to be 9.6 mJ/(mol .K-2) and 450 K. The upper critical filed mu H-0(c2)(0) is estimated to be 0.825 T obtained from rho(T) in several magnetic fields.

DOI： 10.1016/j.physb.2020.412149

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Coexistence of localized and heavy itinerant states in antiferromagnetic CePtGe2

Tomohito Nakano, Shoma Onuma, Naoya Takeda, Klara Uhlirova, Jan Proklesky, Vladimir Sechovsky, Jun Gouchi, Yoshiya Uwatoko

PHYSICAL REVIEW B 100 ( 3 ) 2019.7

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER PHYSICAL SOC

Two conflicting ground states, i.e., an antiferromagnetic ground state at 3.8K and aferromagnetic ground state at 5.1 K, have been reported for CePtGe2, which has two nonequivalent crystallographic Ce sites. In this study, we have prepared polycrystalline and single-crystalline CePtGe2 samples and measured their magnetization, specific heat, resistivity, and Seebeck coefficient. The observed bend in resistivity, peak in magnetic susceptibility, and lambda-type anomaly in specific heat at T-N = 3.8K and the metamagnetic transition in this CePtGe2 suggest antiferromagnetism at low temperatures. No evidence of ferromagnetic order was found in the studied temperature range, indicating possible crystal polymorphism with ferromagnetic character. The large susceptibility around TN and the Schottky-type specific heat indicate a well-localized f -electron state. However, the large residual gamma and X(0) indicate an itinerant heavy f -electron state. These findings suggest the coexistence of localized and heavy itinerant states corresponding to f electrons at the two Ce sites in this antiferromagnetic CePtGe2. The field dependence of magnetization indicates a sudden increase in magnetization at weak magnetic fields (similar to 0.2T), followed by a plateau at fields above 0.2 T, resulting in a possible different polarized metamagnetic state via interaction between localized and itinerant f electrons.

DOI： 10.1103/PhysRevB.100.035107

Web of Science

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Physical properties of EuPdGe single crystal with monoclinic structure

Kambe M., Nagai K., Saito T., Yamauchi N., Hatakeyama A., Minakawa A., Nomoto T., Kase N., Nakano T., Takeda N.

Meeting Abstracts of the Physical Society of Japan 74.2 1928 - 1928 2019

Physical properties of the Antiferromagnetic Compound CePtGe2 under pressure II

Gouchi J., Onuma S., Nakano T., Takeda N., Uwatoko Y.

Meeting Abstracts of the Physical Society of Japan 74.1 1978 - 1978 2019

Fundamental properties of a new samarium compound SmPtSi2 Reviewed

Shuto Yamaguchi, Eisuke Takahashi, Naoki Kase, Tomohito Nakano, Naoya Takeda, Kazuyuki Matsubayashi, Yoshiya Uwatoko

Physica B: Condensed Matter 536 297 - 299 2018.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier B.V.

We have discovered a new orthorhombic ternary compound SmPtSi2. We succeeded in growing a single crystal of SmPtSi2
prepared a polycrystalline sample of this compound, and measured their susceptibility, specific heat, and resistivity. The temperature dependence of susceptibility of the polycrystalline sample is close to that of Sm3+ at high temperatures, and its specific heat shows anomalies at TH = 8.6 K and TL = 5.6 K. The resistivity of a single crystal of SmPtSi2 shows a hump-type anomaly just below TH and a sudden decrease at TL, indicating that these anomalies are intrinsic and that SmPtSi2 exhibits a two-step transition.

DOI： 10.1016/j.physb.2017.10.028

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Thermal expansion and magnetostriction of clathrate compound Pr3Pd20Ge6 Reviewed

K.Matsumoto, Y.Sekiguchi, O.Iwakami, T.Ono, S.Abe, G.Ano, M.Akatsu, K.Mitsumoto, Y.Nemoto, T.Goto, N.Takeda, H.Kitazawa

J.Phys.:Conf. Series 969 012120-1 - 012120-6 2018.4

Superfluidity of 4He in dense aerogel studied using quartz tuning fork Reviewed

K Matsumoto, Y Sekiguchi, O Iwakami, T Ono, S Abe, G Ano, M Akatsu, K Mitsumoto, Y Nemoto, T Goto, N Takeda, H Kitazawa

J. Phys.: Conf. Ser. 969 12019 2018

Single-crystal growth of α-Mn and its physical properties under pressure

Tomaru A., Fukuhara K., Nakano T., Takeda N., Amakai Y., Murayama S.

Meeting Abstracts of the Physical Society of Japan 73 ( 0 ) 541 - 541 2018

Thermoelectric properties of 1T-Ta(S1-xSex)

Araki R., Matsumoto K., Nakano T., Takeda N.

Meeting Abstracts of the Physical Society of Japan 73 ( 0 ) 1568 - 1568 2018

Physical properties of BaTSi (T = Pd, Pt) with non-centrosymmetric structure

Kimura Y., Hosomichi M., Nakano T., Takeda N.

Meeting Abstracts of the Physical Society of Japan 73 ( 0 ) 1187 - 1187 2018

Anisotropic superconductivity of Lu5T6Sn18(T = Co, Ir) with cage structure

Watanabe K., Anada T., Nakano T., Takeda N.

Meeting Abstracts of the Physical Society of Japan 73 ( 0 ) 1188 - 1188 2018

Measurement of the electrical resistivity of the Antiferromagnetic Compound CePtGe2

Gouchi J., Onuma S., Nakano T., Takeda N., Uwatoko Y.

Meeting Abstracts of the Physical Society of Japan 73 ( 0 ) 1518 - 1518 2018

Single crystal growth of transition metal oxide BaIrO3 and its properties

Domon Y., Kawai K., Nakano T., Takeda N.

Meeting Abstracts of the Physical Society of Japan 73 ( 0 ) 609 - 609 2018

Sample preparation of SmPtSi2and its fundamental properties

Yamaguchi S., Takahashi E., Nakano T., Takeda N., Matsubayashi K., Uwatoko Y., Uhlirova K., Pronkleska J., Sechovsky V.

Meeting Abstracts of the Physical Society of Japan 73 ( 0 ) 1714 - 1714 2018

Superconducting gap symmetry of the BiS2-based superconductor LaO0.5F0.5BiSSe elucidated through specific heat measurements Reviewed

Naoki Kase, Yusuke Terui, Tomohito Nakano, Naoya Takeda

PHYSICAL REVIEW B 96 ( 21 ) 2017.12

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER PHYSICAL SOC

In this study, the superconducting gap symmetry of LaO0.5F0.5BiSSe is elucidated through specific heat measurements with one single crystal of LaO0.5F0.5BiSSe. A clear jump is observed at 3.95 K in LaO0.5F0.5BiSSe, suggesting bulk superconductivity. From specific heat measurements, Delta C-e/gamma T-c and 2 Delta(0)/k(B)T(c) are obtained as 2.31 and 4.5. These values indicate strong electron-phonon coupling superconductivity. The temperature (T) and magnetic-field (H) dependence of the electronic specific heat C-e(T, H) suggests that superconductivity is fully gapped. Our handmade system successfully elucidates superconducting gap symmetry of the BiS2-based compound with a small single crystal.

DOI： 10.1103/PhysRevB.96.214506

Web of Science

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Upper critical field of the single crystal La(O,F)BiSe2 Reviewed

Y.Terui, N.Kase, T.Nakano, N.Takeda

J.Phys.: Conf.Series 871 012005-1 - 012005-5 2017.7

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Papers - TAKEDA Naoya