博士(理学), 青山学院大学

自然科学一般, 磁性、超伝導、強相関系

1998年04月 - 2003年03月
青山学院大学, 理工学研究科, 物理学専攻

1992年03月
富山中部高等学校

Two-gap superconducting states of LaRu3Si2
T. Ushioda; T. Muranaka
責任著者, Physica C: Superconductivity and its Applications, Elsevier BV, 625巻, 掲載ページ 1354583-1354583, 出版日 2024年10月, 査読付
研究論文（学術雑誌）

Superconducting properties of pt-type and bct-type YRh₄B₄
K Kurata; T Muranaka
ラスト(シニア)オーサー, Superconductor Science and Technology, IOP Publishing, 36巻, 8号, 掲載ページ 085005-085005, 出版日 2023年06月22日, 査読付, Abstract

YRh₄B₄, which exhibits high-$T _{\mathrm{c } }$ superconductivity in the RRh₄B₄ system, has two types of crystal structures, CeCo₄B₄ type (pt-type) and LuRu₄B₄ type (bct-type). Both types of structure have similar $T _{\mathrm{c } }$ (pt-type; $T _{\mathrm{c } }$ = 10.6 K, bct-type; $T _{\mathrm{c } }$ = 9.8 K), but the $\mu_0 H _{\mathrm{ { c2 } } }$ of both compounds is very different, pt-type; $\mu_0 H _{\mathrm{ { c2 } } }$ = 2.50 T and bct-type; $\mu_0 H _{\mathrm{ { c2 } } }$ = 9.85 T. From our results, one can see that the difference in $T _{\mathrm{c } }$ between pt-YRh₄B₄ and bct-YRh₄B₄ is mainly caused from the difference of the density of state at Fermi energy. The high-$T _{\mathrm{c } }$ in pt-YRh₄B₄ is derived from the high Debye temperature caused by vibrations of boron. In contrast, in bct-YRh₄B₄ it is caused by a stronger electron–phonon coupling than in pt-YRh₄B₄. Regarding the symmetry of superconductivity, it is suggested that pt-YRh₄B₄ is a clean limit superconductor and has basically a fully gapped superconducting gap, but is slightly anisotropic from the results of $C_{\textrm {el } } \propto \textrm {exp}( -\Delta / k_{\mathrm{B } } T$) below $T _{\mathrm{c } }$ and $\Delta \gamma (H) \propto H^{0.65}$. However, bct-YRh₄B₄ is a dirty limit superconductor and has an anisotropic superconducting gap from the results of $C_{\textrm {el } } \propto T^{3}$ below $T _{\mathrm{c } }$ and $\Delta \gamma (H)\propto H$.
研究論文（学術雑誌）

Superconductivity in a new layered triangular-lattice systemLi2IrSi2
K. Horigane; K. Takeuchi; D. Hyakumura; R. Horie; T. Sato; T. Muranaka; K. Kawashima; H. Ishii; Y. Kubozono; S. Orimo; M. Isobe; J. Akimitsu
New Journal of Physics, IOP Publishing, 21巻, 掲載ページ 093056, 出版日 2019年09月24日, 査読付
研究論文（学術雑誌）, 英語

Superconductivity in Carbide Compounds
Takahiro Muranaka; Jun Akimitsu
Chemical Science Journal, 7巻, 3号, 掲載ページ 1000135, 出版日 2016年, 査読付
研究論文（学術雑誌）, 英語

Superconductivity in 122 antimonide SrPt₂Sb₂
Motoharu Imai; Satoshi Emura; Mitsuaki Nishio; Yoshitaka Matsushita; Soshi Ibuka; Naoya Eguchi; Fumihiro Ishikawa; Yuh Yamada; Takahiro Muranaka; Jun Akimitsu
Superconductor Science and Technology, IOP Publishing, 26巻, 7号, 掲載ページ 075001-075001, 出版日 2013年05月14日, 査読付
研究論文（学術雑誌）

Effect of the counter-anion on the spin-transition properties of a family of Fe(ii) tetrazole complexes, [Fe(i4tz)<inf>6</inf>]X<inf>2</inf> (X = ClO <inf>4</inf>^-, PF<inf>6</inf>^-, SbF<inf>6</inf> ^-, BF<inf>4</inf>^-)
Myrvete Tafili-Kryeziu; Matthias Weil; Takahiro Muranaka; Azzedine Bousseksou; Miki Hasegawa; Akimitsu Jun; Wolfgang Linert
Dalton Transactions, Royal Society of Chemistry, 42巻, 44号, 掲載ページ 15796-15804, 出版日 2013年, 査読付, The monodentate ligand 1-isobutyl-1H-tetrazole (i4tz) was used to synthesize a series of iron(ii) spin-crossover (SCO) complexes with the general formula [Fe(i4tz)<
inf>
6<
/inf>
]X<
inf>
2<
/inf>
, where X = ClO<
inf>
4<
/inf>
<
sup>
-<
/sup>
(1), PF<
inf>
6<
/inf>
<
sup>
-<
/sup>
(2), SbF<
inf>
6<
/inf>
<
sup>
-<
/sup>
(3), or BF<
inf>
4<
/inf>
<
sup>
-<
/sup>
(4). Upon cooling, magnetic susceptibility measurements of compounds 1, 2 and 3 show a reversible one-step spin crossover (SCO) behaviour between HS (S = 2) and LS (S = 0) states without hysteresis. The ClO<
inf>
4<
/inf>
<
sup>
-<
/sup>
compound shows a gradual spin transition at T <
inf>
1/2<
/inf>
= 208 K at a considerably higher temperature than the other compounds. The larger anions PF<
inf>
6<
/inf>
<
sup>
-<
/sup>
(T<
inf>
1/2<
/inf>
= 114 K) and SbF<
inf>
6<
/inf>
<
sup>
-<
/sup>
(T<
inf>
1/2<
/inf>
= 116 K) show more gradual transitions, and a "frozen-in effect" was observed after fast cooling. The crystal structure of [Fe(i4tz)<
inf>
6<
/inf>
](SbF<
inf>
6<
/inf>
)<
inf>
2<
/inf>
(3) was determined at 296, 200 and 100 K, revealing a reversible first-order phase transition between 200 and 100 K, accompanied by a triplication of the unit cell volume at 100 K. Temperature-dependent vibration and electronic spectroscopic measurements of compound 1 were compared with the magnetic susceptibility measurements. © The Royal Society of Chemistry 2013.
研究論文（学術雑誌）, 英語

Superconductivity in Lu2SnC
S. Kuchida; T. Muranaka; K. Kawashima; K. Inoue; M. Yoshikawa; J. Akimitsu
Physica C: Superconductivity and its Applications, 494巻, 掲載ページ 77-79, 出版日 2013年, 査読付, We discovered the superconductivity in Lu2SnC with the T c of 5.2 K. Lu2SnC crystallizes in a hexagonal structure (Cr2AlC-type) with the space group of P63/mmc. We measured the physical properties of Lu2SnC in the superconducting state as functions of temperature and magnetic field. The M-H curve shows the typical type-II superconducting behavior. Superconducting parameters Hc1(0), Hc2(0), λ(0), ξ(0) and κGL are determined to be about 110 Oe, 4.5 kOe, 250 nm, 27 nm, and 9.2, respectively. © 2013 Elsevier B.V. All rights reserved.
研究論文（学術雑誌）, 英語

Superconductivity in MgB2
Takahiro Muranaka; Jun Akimitsu
Zeitschrift fur Kristallographie, 226巻, 4号, 掲載ページ 385-394, 出版日 2011年04月, 査読付, We review superconductivity in MgB2 in terms of crystal and electronic structure, electron-phonon coupling, two-gap superconductivity and application. Finally, we introduce the development of new superconducting materials in related compounds. © by Oldenbourg Wissenschaftsverlag, München.
研究論文（学術雑誌）, 英語

Superconductivity in MgB2
Takahiro Muranaka; Jun Akimitsu
ZEITSCHRIFT FUR KRISTALLOGRAPHIE-CRYSTALLINE MATERIALS, WALTER DE GRUYTER GMBH, 226巻, 4号, 掲載ページ 385-394, 出版日 2011年, 査読付, We review superconductivity in MgB2 in terms of crystal and electronic structure, electron-phonon coupling, two-gap superconductivity and application. Finally, we introduce the development of new superconducting materials in related compounds.
研究論文（学術雑誌）, 英語

Pressure-induced high-T-c superconducting phase in FeSe: Correlation between anion height and T-c
H. Okabe; N. Takeshita; K. Horigane; T. Muranaka; J. Akimitsu
PHYSICAL REVIEW B, AMER PHYSICAL SOC, 81巻, 20号, 出版日 2010年05月, In this study, we performed high-pressure electrical resistivity measurements of polycrystalline FeSe in the pressure range of 1-16.0 GPa at temperatures of 4-300 K. A precise evaluation of T-c from zero-resistivity temperatures revealed that T-c shows a slightly distorted dome-shaped curve with maximum T-c(offset) (30 K) at 6 GPa. With the application of pressure, the temperature dependence of resistivity above T-c changes dramatically to a linear dependence, that the high-T-c phase appears above 3 GPa. We found a striking correlation between T-c and the Se height: the lower the Se height, the more enhanced is T-c. Moreover, this relation is broadly applicable to other iron pnictides, strongly indicating that high-temperature superconductivity can appear only around the optimum anion height (similar to 1.38 angstrom). On the basis of these results, we suggest that the anion height should be considered as a key determining factor of T-c of iron-based superconductors containing various anions.
研究論文（学術雑誌）, 英語

Superconductivity in the Ternary Germanide Y3Pt4Ge6
Naoki Kase; Takahiro Muranaka; Jun Akimitsu
J PHYS SOC JPN, 77号, 掲載ページ 054714, 出版日 2008年05月, 査読付
英語

Thermodynamic properties of ferromagnetic Ce-compound, CeAgAl3
Takahiro Muranaka; Jun Akimitsu
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, ELSEVIER SCIENCE BV, 460巻, 掲載ページ 688-690, 出版日 2007年09月, 査読付, We successfully synthesized a new ferromagnetic Ce-compound, CeAgAl3 (T-C = 3.0 K). From susceptibility measurement using the aliened crystal, effective Bohr magneton, mu(eff), and Weiss temperature, theta, were estimated to be about 2.23 mu(B) and 10.1 K along ab-plane, respectively, indicating the tri-valent state for Cc and weak ferromagnetic interaction between Ce ions. In M-H curve, the magnetization along the ab-plane and the c-axis up to 5 T at 1.8 K exhibited ferromagnetic behaviour saturating over 0.2 T with small magnetic hysteresis and reached the values of about 1.07 mu(B) and 0.75 mu(B), respectively. These values are somewhat smaller than the theoretical value for the saturated moment of free Ce3+ ion (mu(s) = gJ = 2.14 mu(B)). (C) 2007 Elsevier B.V. All rights reserved.
研究論文（学術雑誌）, 英語

Scanning tunnelling microscopy and spectroscopy of MgB2
Toshikazu Ekino; Tomoaki Takasaki; Raquel Ribeiro; Takahiro Muranaka; Jun Akimitsu
Journal of Physics: Conference Series, Institute of Physics Publishing, 61巻, 1号, 掲載ページ 278-282, 出版日 2007年04月01日, 査読付, Experiments of the scanning tunnelling microscopy and spectroscopy (STM/STS) have been carried out on the layered superconductor MgB2 with Tc 39 K. The measurements were done at 5 K using a Pt-Ir tip and the single-crystal grain. The STM images show characteristic hexagonal patterns with the distances of nearest neighbour atoms to be 0.3 - 0.35 nm and 0.15 - 0.2 nm, respectively, which are consistent with the Mg and B lattice sizes. The STS measurements clarify the superconducting gap 2Δ 20 - 24 meV, which leads to the strong-coupling ratio 2Δ/kBTc 5 - 6. The tunnelling spectra can be described by the correlated 2-gap model. These features are consistent with our previous break-junction measurements. The gap structure is homogeneous at least within the range of 200 nm × 200 nm. © 2007 IOP Publishing Ltd.
研究論文（学術雑誌）, 英語

Superconductivity in magnesium diboride and its related materials
Satoshi Akutagawa; Takahiro Muranaka; Jun Akimitsu
ELECTRON CORRELATION IN NEW MATERIALS AND NANOSYSTEMS, SPRINGER, 241巻, 掲載ページ 73-+, 出版日 2007年, 査読付, After the discovery of MgB2, much attention has been paid to the boride and carbide systems. In this paper, we mainly review the following subjects. First, we review the present situation of the superconductivity in MgB2, which can be interpreted in terms of BCS-type phonon-mediated pairing. In particular, we focus on the relationship between the superconductivity and the electronic structure in MgB2 and two gap feature. Second, we review our present status for the new superconductors including the carbon systems. Recently, we have reported a relatively high-T-c superconductivity in Y2C3 at 18 K whose T-c could be changed by synthesis conditions from 10 to 18 K [J. Phys. Soc. Jpn. 73 (2004) 530.]. We synthesized a high-purity sample of the medium-T-c phase (T-c=13.9 K) in Y2C3 and examined its physical properties. From a specific heat measurement, square C(T-c)/gamma T-c value is calculated to be 3.3 and the superconducting gap is estimated to be 2 square/k(B)T(c) = 4.5, indicating that the superconductivity in Y2C3 can be described by s-wave strong coupling regime. From specific heat in various magnetic fields, the upper critical field H-c2(0) is estimated to be 24.7 T.
研究論文（国際会議プロシーディングス）, 英語

Superconductivity in M7Re13X (M = W, Mo, X = B, C) compounds
K Kawashima; A Kawano; T Muranaka; J Akimitsu
PHYSICA B-CONDENSED MATTER, ELSEVIER SCIENCE BV, 378-80巻, 掲載ページ 1118-1119, 出版日 2006年05月, 査読付, We discovered a series of new superconductors, M7Re13X (M = W, Mo, X = B, C), and discussed their superconducting properties. M7Re13X (M = W, Mo, X = B, C) has a beta-Mn-type (Cubic, P(4)I32) structure. The T-c values are 7.1 K for W7Re13B, 7.3 K for W7Re13C, 8.3K for Mo7Re13B and 8.1 K for Mo7Re13C. The magnetization vs. magnetic field curve showed type-II superconducting behavior. These superconductors can be described as strong coupling regime and Re orbital is mainly responsible for the superconductivity of these compounds. (c) 2006 Elsevier B.V. All rights reserved.
研究論文（学術雑誌）, 英語

Superconductivity in intermetallic compound Mo7Re13X(X = B,C)
K Kawashima; T Muranaka; J Akimitsu
SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS, NATL INST MATERIALS SCIENCE, 7巻, 1号, 掲載ページ 9-11, 出版日 2006年01月, 査読付, We report here the physical properties of a new intermetallic superconductor Mo7Re13X(X=B,C) (T-c=8.3 K (X=B) and 8.1 K (X=C)). The crystal structure of Mo7Re13X is the beta-Mn-type (cubic, space group: P4(1)32) and the Re atoms form a tilted octahedron. The magnetization (M-H) curves show a typical type-II superconductivity; the lower critical field H-c1(0), upper critical field H-c2(0) and Ginzburg-Landau (GL) parameter value k are, respectively, 3.0 Oe, 15.4 T and 101 for X=B and 3.1 Oe, 14.8 T and 98 for X=C. The superconducting gap versus k(B)T(C): 2 Delta/k(B)T(c) values are 4.4 for X=B and 4.2 for X=C, which implies that superconductivity in Mo7Re13X(X=B,C) can be described by an s-wave strong coupling regime. (c) 2005 Elsevier Ltd. All rights reserved.
研究論文（学術雑誌）, 英語

Point-contact spectroscopy measurements of binary superconductor MgB2
T Takasaki; T Ekino; RA Ribeiro; T Muranaka; H Fujii; J Akimitsu
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, ELSEVIER SCIENCE BV, 426巻, 掲載ページ 300-303, 出版日 2005年10月, 査読付, We studied the superconductor MgB2 by point-contact spectroscopy. The first derivative conductance of the current (I)-voltage (V) characteristics dI/dV(V) displays the Andreev reflection features at the superconductor-normal metal interface. The largest gap values are estimated to be Delta(4.2 K) = 9-12 meV. We also observed clear evidences for the multiple-gaps feature with the small gap Delta(4.2 K) = 1-3 meV. These gap values agree with the previous break-junction data. The observed peak positions in the second derivative conductance (d(2)I/dV(2)(V)) are consistent with the phonon density of states of inelastic neutron scattering measurements. (c) 2005 Elsevier B.V. All rights reserved.
研究論文（学術雑誌）, 英語

Spatially heterogeneous character of superconductivity in MgB2 as revealed by local probe and bulk measurements
T Ekino; AM Gabovich; MS Li; T Takasaki; AI Voitenko; J Akimitsu; H Fujii; T Muranaka; M Pekala; H Szymczak
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, ELSEVIER SCIENCE BV, 426巻, 掲載ページ 230-233, 出版日 2005年10月, 査読付, Controversial tunnel and point-contact experimental data on superconducting gap values in MgB2 are analyzed and interpreted in terms of the spatial inhomogeneity and the proximity effect appropriate to this layered compound. Existing specific heat measurements are explained in the same way. Break-junction tunnel studies of polycrystalline MgB2 samples are carried out and a clear-cut multiplicity of gaps is observed, although the shapes of the I-V characteristics vary substantially. (c) 2005 Published by Elsevier B.V.
研究論文（学術雑誌）, 英語

Manifestations of inhomogeneity in MgB2: from specific heat to tunnel measurements
T Ekino; AM Gabovich; MS Li; T Takasaki; AI Voitenko; J Akimitsu; H Fujii; T Muranaka; M Pekala; H Szymczak
PHYSICA B-CONDENSED MATTER, ELSEVIER SCIENCE BV, 359巻, 掲載ページ 460-462, 出版日 2005年04月, 査読付, Tunnel conductances of superconducting polycrystalline MgB2 samples were measured by the break-junction technique. Three main gap-like peculiarities are observed, while other ones scatter from sample to sample. These results correlate with heat capacity measurements, an analysis which shows a wide range of energy gaps involved. (c) 2005 Published by Elsevier B.V.
研究論文（学術雑誌）, 英語

Superconductivity in intermetallic W7Re13X (X = B and C) compounds
K Kawashima; A Kawano; T Muranaka; J Akimitsu
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, PHYSICAL SOC JAPAN, 74巻, 2号, 掲載ページ 700-704, 出版日 2005年02月, 査読付, We discovered superconductivity in W7Re13X (X = B and C) (T-c = 7.1 K and 7.3 K, respectively), and their superconducting properties are discussed. The crystal structure of W7Re13X is beta-Mn-type (cubic, space group: P4(1)32), and Re atoms form a tilted octahedron. The magnetization (M-H) curves show typical type-II superconducting behavior, and the lower critical field H-c1(0), the upper critical field H-c2(0) and the Ginzburg-Landau (GL) parameter kappa are 7.7 mT, 11.4 T and 54 for X = B and 4.0 mT, 12.6 T and 80 for X = C, respectively. From the specific heat measurement, the superconducting gap magnitudes are estimated to be 2Delta/k(B)T(c) = 4.28 and 4.02, respectively.
研究論文（学術雑誌）, 英語

Superconductivity in MgB2 and its related materials
J Akimitsu; S Akutagawa; K Kawashima; T Muranaka
PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT, PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, 159号, 掲載ページ 326-337, 出版日 2005年, 査読付, After the discovery of MgB2, much attention has been paid to the boride and carbide systems. In this paper, we mainly review the following themes. First, we review the present situation of the superconductivity in MgB2, which can be interpreted in terms of BCS-type phonon mediated pairing. In particular, we focus on the relationship between the superconductivity and the crystal structure in MgB2 and two gap feature. Second, we review our present status for the new superconductors including the boron and carbon systems. Recently, we discovered new superconductivity in related compounds W7Re13X (X = B and C) (T, = 7.1 K and 7.3 K, respectively) and Y2C3 (T = 18 K), and we elucidated their superconducting properties. The crystal structure Of W7Re13X (X = B and C) is beta-Mn type (cubic, space group: P4(1)32), and Re atoms form a distorted octahedron. The superconductivity in W7Re13X system is recognized as strong coupling s-wave symmetry from the specific heat measurement. We discovered the superconductivity at T-c = 18 K in Y2C3, although this material with a maximum T-c of 11.5 K has already investigated by Krupka et al. The crystal structure Of Y2C3 is body centered cubic (Pu2C3-type) structure, and Y atoms are one-dimensionally aligned along [111] axis. The lattice parameter, alpha, obtained in our work is between 8.18-8.23 angstrom, and is smaller than those previously reported (8.21-8.25 angstrom).
研究論文（学術雑誌）, 英語

Superconductivity in MgB2
Jun Akimitsu; Takahiro Muranaka
Physica C: Superconductivity and its Applications, 388-389巻, 掲載ページ 98-102, 出版日 2003年05月, 査読付, We recently discovered that the intermetallic compound magnesium diboride (MgB2) exhibits the highest superconducting transition temperature (Tc = 39 K) of all the metallic superconductors. In this paper we report on the basic superconducting characteristics of MgB2 and the current status of the research for the unanswered problem in this superconductivity. Especially, we review the several reports for the superconducting gap (Δ) by the spectroscopic measurements. Moreover we introduce the research into its anisotropic parameter (γ), which is important for the understanding of this superconducting states in this material. © 2003 Elsevier Science B.V. All rights reserved.
研究論文（国際会議プロシーディングス）, 英語

Electronic structure of (formula presented)X-ray emission and absorption studies
E. Z. Kurmaev; I. I. Lyakhovskaya; J. Kortus; A. Moewes; N. Miyata; M. Demeter; M. Neumann; M. Yanagihara; M. Watanabe; T. Muranaka; J. Akimitsu
Physical Review B - Condensed Matter and Materials Physics, 65巻, 13号, 掲載ページ 1-4, 出版日 2002年, 査読付, Measurements of x-ray emission and absorption spectra of the constituents of (formula presented) are presented. The results obtained are in good agreement with calculated x-ray spectra, with dipole matrix elements taken into account. The comparison of x-ray emission spectra of graphite, (formula presented) and (formula presented) in the binding energy scale supports the idea of charge transfer from (formula presented) to (formula presented) bands, which creates holes at the top of the bonding (formula presented) bands and drives the high-(formula presented) superconductivity in (formula presented). © 2002 The American Physical Society.
研究論文（学術雑誌）

Grain boundaries as weak links: The case of (formula presented) with reference to (formula presented)
S. B. Samanta; H. Narayan; A. Gupta; A. V. Narlikar; T. Muranaka; J. Akimitsu
Physical Review B - Condensed Matter and Materials Physics, 65巻, 9号, 掲載ページ 1-3, 出版日 2002年, 査読付, The grain boundaries (GB’s) in the intermetallic superconductor (formula presented) interestingly, do not show suppression of supercurrent density. This unexpected behavior has been investigated by a scanning tunneling microscopy/spectroscopy technique at atomic resolution. The GB in (formula presented) is seen as an amorphous region extending from 50 to 200 Å and has a metallic character. This observation supports proximity coupling between the grains, which explains why supercurrent density does not degrade in this material. The results for another intermetallic superconductor (formula presented) having GB’s (average width 30 Å) that are quasi-insulating in nature have also been presented and compared with the former. © 2002 The American Physical Society.
研究論文（学術雑誌）, 英語

Evidence for high-frequency phonon mediated S-wave superconductivity: (formula presented) NMR study of Al-doped (formula presented)
H. Kotegawa; K. Ishida; Y. Kitaoka; T. Muranaka; N. Nakagawa; H. Takagiwa; J. Akimitsu
Physical Review B - Condensed Matter and Materials Physics, 66巻, 6号, 掲載ページ 1-6, 出版日 2002年, 査読付, We report (formula presented) NMR studies that address the underlying two superconducting (SC) gaps model and a possible mechanism for interpreting a high SC transition temperature (formula presented) of (formula presented) in a recently discovered (formula presented) We reported in a previous paper [Phys. Rev. Lett. (formula presented) 127001 (2001)] that the results of the nuclear-spin-lattice relaxation rate, (formula presented) in the SC state revealed the existence of a single large SC gap with (formula presented) This conclusion is corroborated by the calculation that any two-gap models cannot account for the experimental results. In Al-doped (formula presented) the result of (formula presented) in the SC state revealed that a size in the SC gap is not changed by substituting Al for Mg. The reduction in (formula presented) by Al doping is shown to be due to the decrease of the density of states (formula presented) at the Fermi level. According to the McMillan equation, an experimental relation between (formula presented) and the relative change in (formula presented) allowed us to estimate a characteristic phonon frequency (formula presented) and an electron-phonon coupling constant (formula presented) These results suggest that the high- (formula presented) superconductivity in (formula presented) is mediated by the strong electron-phonon coupling with high-frequency phonons. © 2002 The American Physical Society.
研究論文（学術雑誌）, 英語

Strong coupling s-wave superconductivity in MgB2: B-11-NMR Study of MgB2 and Al-doped MgB2
Hisashi Kotegawa; Kenji Ishida; Yoshio Kitaoka; Takahiro Muranaka; Norimasa Nakagawa; Hiroyuki Takagiwa; Jun Akimitsu
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, PHYSICAL SOC JAPAN, 71巻, 掲載ページ 332-334, 出版日 2002年01月, 査読付, We have measured nuclear spin-lattice relaxation time, T-1 of B-11 in MgB2 and Al-doped MgB2. TIT const, behavior is observed in the normal state, indicating the absence of strong magnetic correlation. In the superconducting (SC) state of MgB2, 1/T-1 shows a tiny coherence peak just below T. and decreases exponentially with a large SC gap of 2 Delta/k(B)T(c) similar to 5.These results suggest that MgB2 is a strong coupling s-wan superconductor. As Al3+ is doped into Mg2+ site,T1T which is proportional to the square of the density of states (DOS) decreases. The variation of T, against the DOS deduced from 1/T1T is fitted by McMillan equation, and the Debye frequency w and the electron-phonon coupling constant A were estimated as 700 K and 0.87, respectively. Both are in good agreement with the values from theoretical works. The high-T-c. superconductivity in MgB2 is considered to occur through strong coupling between electrons and Ii ugh frequency-phon.on.
研究論文（学術雑誌）, 英語

Thermal transport properties of (formula presented)
T. Muranaka; J. Akimitsu; M. Sera
Physical Review B - Condensed Matter and Materials Physics, 64巻, 2号, 出版日 2001年, 査読付, The thermal transport properties and magnetic susceptibility of (formula presented) have been studied. The thermoelectric power with a positive sign shows a nearly T-linear increase up to ∼150 K but shows a saturated behavior at higher temperatures, which suggests the existence of two types of charge carrier. The magnetic susceptibility above (formula presented) shows a Pauli paramagnetism but shows a substantial T dependence which should include the information of the band structure of (formula presented) The thermal conductivity shows a suppression below (formula presented) without a clear anomaly at (formula presented) which is a result of the reduction of the normal charge carrier concentration below (formula presented) © 2001 The American Physical Society.
研究論文（学術雑誌）, 英語

高圧合成法を用いたアルカリ金属を含む新規超伝導体の探索及び物性評価
竹内 和也; 堀金 和正; 堀江 理恵; 小林 夏野; 村中 隆弘; 磯部 雅朗; 秋光 純
一般社団法人 日本物理学会, 出版日 2019年, 日本物理学会講演概要集, 74.1巻, 掲載ページ 1664-1664, 日本語, 2189-0803, 130008146687

26aPS-130 RTM_4Si_2(R:希土類元素,TM:遷移金属元素)の超伝導(領域8ポスターセッション(理論,空間非対称,アクチノイドなど),領域8(強相関系分野:高温超伝導,強相関f電子系など))
鎌倉 英通; 村中 隆弘
一般社団法人日本物理学会, 出版日 2013年08月26日, 日本物理学会講演概要集, 68巻, 2号, 掲載ページ 531-531, 日本語, 1342-8349, 110009757187, AA11439205

“Multiple-gap structure of the binary superconductor MgB_2”
T.Takasaki; T.Ekino; T.Muranaka; H.Fujii; J.Akimitsu
Electron-tunneling measurements on the superconductor MgB2 with T-c = 39 K have been carried out using a break-junction technique. We have observed the double-gap structures with several combinations of the gap sizes. The largest Delta = 9 meV gap can be observed as a single gap, which gives very strong-coupling ratio 2Delta/k(B)T(c) = 5.3-5.7. (C) 2003 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV, 出版日 2003年05月, Physica, 388巻, 掲載ページ 147-148, 英語, 0921-4534, 1873-2143, WOS:000183340300067

29aYF-1 フェムト秒超高速応答から見た MgB_2 の多重超伝導ギャップ
村上 博成; 斗内 政吉; 村中 隆弘; 秋光 純
一般社団法人 日本物理学会, 出版日 2003年, 日本物理学会講演概要集, 58巻, 0号, 掲載ページ 702-702, 日本語, 110002221189

Physical Properties in Flux Line Lattice State in MgB 2 Probed by μsR
Kazuki Ohishi; Takahiro Muranaka; Jun Akimitsu; Akihiro Koda; Akihiro Koda; Wataru Higemoto; Wataru Higemoto; Ryosuke Kadono; Ryosuke Kadono; Ryosuke Kadono
We have performed muon spin rotation (μSR) measurements to deduce the magnetic penetration depth λbA in the flux line lattice state of M gB2 microscopically. It is observed that λA shows a quadratic temperature dependence which is predicted for the case of superconducting gap with line nodes. Furthermore, it clearly exhibits a strong field dependence, where λ increases almost linearly with H. These results strongly suggest that the superconducting order parameter in M gB2 is highly anisotropic. © 2002 The Physical Society of Japan., 出版日 2002年12月01日, Journal of the Physical Society of Japan, 71巻, 掲載ページ 335-337, 0031-9015, 70349418164

α-Mn型構造の新規HEA超伝導体
中村亮; 村中隆弘
ポスター発表, 日本語, 日本物理学会第79回年次大会
発表日 2024年09月18日

レニウム硼化物の超伝導
日野豊; 倉又健人; 村中隆弘
ポスター発表, 日本語, 日本物理学会第79回年次大会
発表日 2024年09月18日

Re-Ru-X三元素系における構造制御と新規超伝導体の開発
中村亮; 村中隆弘
ポスター発表, 日本語, ⽇本物理学会第78回年次⼤会
発表日 2023年09月18日

W5Si3型構造Nb5Si3のSiサイト置換による超伝導
宮下朋之慎; 越川圭太; 中村亮; 村中隆弘
ポスター発表, 日本語, ⽇本物理学会第78回年次⼤会
発表日 2023年09月18日

金属ReのTc向上
木友希; 中村亮; 村中隆弘
ポスター発表, 日本語, ⽇本物理学会第78回年次⼤会
発表日 2023年09月18日

Re-Ru-Ti系の超伝導
中村亮; 村中隆弘
ポスター発表, 日本語, 日本物理学会 2023年春季大会
発表日 2023年03月24日

(Re,V)2Bの超伝導
倉又健人; 村中隆弘
口頭発表（一般）, 日本語, 日本物理学会 2022年秋季大会
発表日 2022年09月15日

単純正方晶型及び体心正方晶型YRh4B4の超伝導特性
倉田滉平; 村中隆弘
口頭発表（一般）, 日本語, 日本物理学会 第77回年次大会, 国内会議
発表日 2022年03月16日

Superconductivity in intermetallic compounds with light elements
T. Muranaka
口頭発表（招待・特別）, 英語, Materials Research Meeting 2021 (MRM2021), 招待, The Materials Research Society of Japan (MRS-J), Yokohama, 国際会議
発表日 2021年12月16日

Lu2SnCの超伝導特性と電子状態
口田沙織; 川島健司; 村中隆弘; 吉川雅章; 秋光純
ポスター発表, 日本語, 日本物理学会 2013年秋季大会
発表日 2019年09月26日

LaRu3Si2の超伝導対称性
潮田匠史; 村中隆弘
ポスター発表, 英語, 日本物理学会 第74回年次大会
発表日 2019年03月15日

LaRh2Ga2の超伝導
中山遥介; 村中隆弘
ポスター発表, 日本語, 日本物理学会 第74回年次大会
発表日 2019年03月15日

STM/STSによるMgB2超伝導体におけるギャップの温度依存性の観測
柳瀬祐太; 杉本暁; 村中隆弘; 浴野稔一
ポスター発表, 日本語
発表日 2016年09月14日

RTM4Si2（R:希土類元素，TM:遷移金属元素）の超伝導
鎌倉英通; 村中隆弘
ポスター発表, 日本語, 日本物理学会 2013年秋季大会
発表日 2013年09月26日

Superconductivity in intermetallic compounds with light elements
T. Muranaka
口頭発表（招待・特別）, 英語, 25th International Symposium on Superconductivity (ISS2012), 招待
発表日 2012年12月

Superconductivity in wide-gap semiconductors
Takahiro Muranaka
口頭発表（招待・特別）, 英語, The 9th International Conference on Materials and Mechanisms of Superconductivity (M2X-IX), 招待
発表日 2009年09月

固体物性論基礎
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物理学概論第一
2024年04月 - 2024年09月

物理工学実験第二
2023年10月 - 2024年03月

波動と光
2023年10月 - 2024年03月

固体物性論基礎
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物理学概論第一
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日本物理学会

量子ビームを用いたオペランド測定による電池材料中の電荷移動機構の解明
基盤研究(B)一般, 研究分担者
研究期間 2023年04月 - 2026年03月