Presentations -

六方晶層状化合物EuSn2As2の自発分極

平田昂輝，坂上良介，的場正憲，神原陽一

[Domestic presentation]  第43回 日本磁気学会学術講演会, 

2019.09

, 

Poster presentation

二次元近藤格子系EuSn2As2の熱電変換性能

坂上良介, 狩俣春成, 後藤陽介, 東 伸彦, 平田昂輝, 中西 愛, 岩崎 秀, 山口 道太郎, 北脇 樹, 水口佳一, 的場正憲, 神原陽一

[Domestic presentation]  第43回 日本磁気学会学術講演会, 

2019.09

, 

Oral presentation (general)

Computational analysis on magnetic phased of a superconducting layered compound, Sr2VFeAsO3-delta

Y. Tojo, M. Nakanishi, Y. Kamihara

[Domestic presentation]  日本物理学会2019年秋季大会 (岐阜大学) , 

2019.09

, 

Oral presentation (general)

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鉄系層状高温超伝導体の1つであるSr2VFeAsO3 (21113V)1は, ペロブスカイト関連Sr2VO3層とPbO型FeAs層が互いに積層した複合アニオン層状化合物(Mixed anion layered compounds: MALCs)である. 21113Vは, 酸素欠損量()  0.145 の酸素欠損量()を示す化学組成においてバルク超伝導相2を示すのみならず, Powder-in-tube (PIT)法により超電導線材が作製可能3であり, 高機能な酸素発生電気化学触媒4である. すなわち, 多機能な材料といえる. Nakamuraらは, 21113V ( = 0)の安定な磁性相を分子式中の鉄(Fe), バナジウム(V)ともに反強磁性と報告した.5 ところで, 21113Vの安定な磁性相は, の変化に対応し変化する.2 しかしながら, 実験的に得られる  0の化学組成を示す21113Vの磁性相と比較可能な理論的な磁性相モデルは, いまだ不明であった. 我々は, 21113V ( = 0, 0.25, 0.5)の 21113Vにおける酸素欠損由来の磁性相転移の詳細を, 密度汎関数理論(DFT)に基づき報告する. 21113V (0)のVはフェリ磁性を示す.2 21113V (0)は, 低温において常伝導相を示す ~ 0.25において最大の自発磁化を示す.2 21113Vの磁気相図は, DFTに基づき得られた21113V中のFe, Vの理論的なスピン分極により支持される.6

共鳴軟X線散乱によるEu系層状磁性体の磁気構造の解明

平田靖透, 櫻木俊輔, 池田啓祐, 中尾裕則, 山崎裕一, 坂上良介, 神原陽一, 近藤猛, 和達大樹

[Domestic presentation]  日本物理学会2019年秋季大会 (岐阜大学) , 

2019.09

, 

Oral presentation (general)

バルク層状磁性体に生じる非従来型異方的超伝導

櫻木俊輔, 佐々木秀, 明石遼介, 坂上良介, 黒田健太, C. Bareille, 橋本嵩広, 長島椿, 木下雄斗, 平田靖透, 下澤雅明, 浅井晋一郎, 土居抄太郎, 辻本直人, 國定聡, 野口亮, 黒川輝風, 東伸彦, 平田昂輝, T. K. Kim, C. Cacho, 益田隆嗣, 徳永将史, 和達大樹E, 岡﨑浩三, 辛埴, 神原陽一, 山下穣, 近藤猛

[Domestic presentation]  日本物理学会2019年秋季大会 (岐阜大学) , 

2019.09

, 

Oral presentation (general)

Computational chemical analysis on element-specific magnetic phases in a mixed anion layered compound superconductor, Sr2VFeAsO3-delta

Yujiro TOJO, Manami NAKANISHI, Yoichi KAMIHARA

[International presentation]  The 6th Japan-Korea International Seminar on Materials Science and Engineering (JKMST2019) (Sapporo, Japan) , 

2019.08

, 

Oral presentation (invited, special), The Materials Science Society of Japan, Materials Research Society of Korea

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Sr2VFeAsO3δ is a mixed anion layered compound with a thick-blocking layer composed by a perovskite-related vanadium oxide layer. In 2019, an electric and magnetic phase diagram as a function of oxygen deficiency (δ) on superconducting Sr2VFeAsO3δ was experimentally demonstrated. [1] In this study, the magnetic stability of V and Fe in Sr2VFeAsO3δ (δ = 0, 0.25, 0.50) was theoretically verified based on the density functional theory. Stable magnetic phases of the V are antiferromagnetic ordered phase between two ferromagnetic V magnetic layers (so-called A-AFM) for δ = 0. [2] And the stable magnetic phases of V are ferrimagnetic ordered phase (Ferri.) for δ = 0.25, 0.50. [3-5] Magnetic phases of Fe are a stripe-type antiferromagnetic ordered phase (s-AFM) in δ = 0, 0.25, 0.50, although the magnetic phases of the Fe with δ = 0.25 shows almost the same formation energy between s-AFM and paramagnetic (PM) ordered phases. Theoretical magnetic ordered phases are qualitatively consistent with the experimental electronic and magnetic phase diagrams for Sr2VFeAsO3δ, although quantitative differences appear between measured for amounts of element specific magnetic moments and theoretical ones.

Thermoelectric properties of mixed anion layered compoundSr2VFeAsO3-δ (δ = 0.150)

S. Iwasaki, M. Yamaguchi, R. Sakagami, K. Kihou, C. H. Lee, and Y. Kamihara

[International presentation]  The 6th Japan-Korea International Seminar on Materials Science and Engineering (JKMST2019) (Sapporo, Japan) , 

2019.08

, 

Poster presentation, The Materials Science Society of Japan, Materials Research Society of Korea

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Mixed anion layered compound (MALC) Sr2VFeAsO3-δ is one of the iron-based superconductors with an oxygen-deficient perovskite-related crystal structure of Sr2VO3-δ.
The oxygen deficiency (δ) of Sr2VFeAsO3-δ affects to the superconductivity and magnetic ordering : bulk superconductivity with 0.031 =< δ =< 0.145 and V-3d ferrimagnetism with 0.124 =< δ =< 0.631. The ferrimagnetism can possibly enhance the thermoelectrical properties for Sr2VFeAsO3-δ. Sr2VFeAsO3-δ can be a promising thermoelectrical material due to the tenability of carrier by δ, the larger lattice volume and two-dimensional crystal structure. In this report, dimensionless figure of merit (ZT) = ~5×10-5 was demonstrated for Sr2VFeAsO3-δ with δ = 0.150(2), which does not show bulk superconductivity and show V-3d ferrimagnetism. The strategies to enhance ZT for Sr2VFeAsO3-δ will be discussed.

Crystallographic phases in Y0.77Gd0.23Ba2Cu3O7-δ thin film annealed in the range of 573 K to 673 K

S. Kozutsumi, S. Iwasaki, M. Matoba, Y. Kamihara, M. Miura

[International presentation]  The 6th Japan-Korea International Seminar on Materials Science and Engineering (JKMST2019) (Sapporo, Japan) , 

2019.08

, 

Poster presentation, The Materials Science Society of Japan, Materials Research Society of Korea

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In this study, we demonstrate a Temperature (T)-Pressure (P) phase diagram for (Y,Gd)BCO thin film annealed at T = 573 K-673 K. The T-P phase diagram is an essential information to elucidate possible approach to demonstrate such an anion-doped (Y,Gd)BCO thin films. As-grown (Y,Gd)BCO thin films were made by metal organic depositions and processed on the best annealing condition for obtaining the highest transition temperature, 92.5 K. Crystallographic phase of annealed (Y,Gd)BCO thin films were checked by X-ray diffraction (XRD) (Rigaku, RINT2500Ultra18). XRD patterns of (Y,Gd)BCO are shown in the figure. The orthorhombic crystallographic phase of (Y,Gd)BCO thin films appears in a sample annealed at 673 K.

Thermal transport properties of mixed anion layered compound Sr2CrFeAsO3-delta,

H. Karimata, M. Yamaguchi, S. Iwasaki, R. Sakagami, Y. Goto, Y. Mizuguchi, M. Matoba, Y. Kamihara

[International presentation]  The 6th Japan-Korea International Seminar on Materials Science and Engineering (JKMST2019) (Sapporo, Japan) , 

2019.08

, 

Poster presentation, The Materials Science Society of Japan, Materials Research Society of Korea

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Sr2CrFeAsO3-δ consists of a carrier conducting FeAs layer and carrier blocking Sr2CrO3-δ layer. Polycrystalline Sr2CrFeAsO3-δ samples were prepared by a solid-state reaction. And hot-pressed (HP) Sr2CrFeAsO3-δ (δ=0.250) were prepared from polycrystalline Sr2CrFeAsO3-δ. The amounts of oxygen deficiency (δ) for the polycrystalline and HP samples were determined assuming a linear relation between δ and lattice volume (V). The c axis of HP Sr2CrFeAsO3-δ sample is slightly oriented along the pressure direction. Transport properties of HP Sr2CrFeAsO3-δ were measured at temperature (T) = 300?673 K. HP Sr2CrFeAsO3-δ exhibits a maximum electrical resistivity (ρ) 58 mΩ cm at 473 K. HP Sr2CrFeAsO3-δ also exhibits a minimum thermal conductivity (κ) 3.5 W m?1 K?1 at 300 K.

Spontaneous magnetic polarization of a layered hexagonal compound, EuSn2As2

K. Hirata, R. Sakagami, M. Matoba, Y. Kamihara

[International presentation]  The 6th Japan-Korea International Seminar on Materials Science and Engineering (JKMST2019) (Sapporo, Japan) , 

2019.08

, 

Poster presentation, The Materials Science Society of Japan, Materials Research Society of Korea

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EuSn2As2 is magnetic material that was reported by Arguilla et al in 2017. The crystal structure of
EuSn2As2 is classified in hexagonal lattice, and the space group is R3-m. In EuSn2As2, a layer of Eu2+
and two [Sn2As2]2- layers are alternately stacked by van der Waals attractoin force. In 2019, EuSn2P2
whose crystallographic structures are identical to EuSn2As2, was reported by Gui et al. Such kinds
of crystallographic structures have been focused as candidates for thermoelectric materials from
1954. At present, these are studied again as a candidate substance for which topological transport
phenomena may be observed. In this symposium, we demonstrate magnetization (M) as a function of
magnetic field (H), Arrott plot, and temperature (T) dependence of spontaneous magnetic polarization
(Ms) for polycrystalline EuSn2As2.

Several possible electronic phases in FeS and SrTiO3 interface based on density functional theory

K. Watanabe, S. Higashi, M. Nakanishi, M. Matoba, Y. Kamihara

[International presentation]  The 6th Japan-Korea International Seminar on Materials Science and Engineering (JKMST2019) (Sapporo, Japan) , 

2019.08

, 

Poster presentation, The Materials Science Society of Japan, Materials Research Society of Korea

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We demonstrate a possible electronic structures of the FeSe molecule layers whose properties are dominated by structures in the interface between FeSe and substrates based on density functional theory.

層状オキシカルコゲナイドLaCuChO (Ch = S, Se, Te)の熱伝導率に対する非調和格子動力学による理論検証

北脇樹，中西愛，神原陽一

[Domestic presentation]  日本材料科学会主催 2019年度学術講演大会 (関東学院大学KGU関内メディアセンター8階 （神奈川県横浜市中区太田町2-23）) , 

2019.05

, 

Oral presentation (general), 日本材料科学会

密度汎関数理論による酸素発生触媒CaCu3Fe4O12の水分子吸着能評価

河嶋丈富，中西愛，渡邉健太郎, 神原陽一，的場正憲

[Domestic presentation]  日本材料科学会主催 2019年度学術講演大会 (関東学院大学KGU関内メディアセンター8階 （神奈川県横浜市中区太田町2-23）) , 

2019.05

, 

Oral presentation (general), 日本材料科学会

酸素欠損を持つCaTiO3の密度汎関数理論による熱力学的安定性評価

青木佑介，中西愛，渡邉健太郎，神原陽一

[Domestic presentation]  日本材料科学会主催 2019年度学術講演大会 (関東学院大学KGU関内メディアセンター8階 （神奈川県横浜市中区太田町2-23）) , 

2019.05

, 

Oral presentation (general), 日本材料科学会

低温で熱処理された銅酸化物超伝導体Y0.77Gd0.23Ba2Cu3O7-δ薄膜の結晶相評価

小堤渉平，岩崎秀，的場正憲，神原陽一，三浦正志

[Domestic presentation]  日本材料科学会主催 2019年度学術講演大会 (関東学院大学KGU関内メディアセンター8階 （神奈川県横浜市中区太田町2-23）) , 

2019.05

, 

Poster presentation, 日本材料科学会

Observation of magnetically combined two-dimensional electronic states in a bulk layered antiferromagnet EuSn2As2

S. Sakuragi, R. Sakagami, K. Kuroda, C. Bareille, N. Azuma, T. Iwatake, S. Sasaki, S. Doi, N. Tsujimoto, R. Akashi, S. Kunisada, R. Noguchi, K. Kurokawa, T. K. Kim, C. Cacho, S. Shin, Y. Kamihara, and T. Kondo

[Domestic presentation]  日本物理学会 第74回年次大会（2019年） (〒819-0395 福岡市西区元岡744 九州大学伊都キャンパス) , 

2019.03

, 

Oral presentation (general)

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近年、新奇機能性材料の創出の観点から、機能性二次元材料をファンデルワールス力により積層した層状物質が注目を集めている。これらの物質系では、層間の電気的、光学的、またスピン軌道結合を自在に設計し、制御することが可能になると期待される。このような観点から、我々は二次元(層内)強磁性Eu 層により二枚のSnAs 層が挟まれたEuSn2As2に関して研究を行った。

熱電物質LaOBiS2-xSexにおける電子・局所結晶構造の分光測定

寺嶋健成, 矢野佑幸, Paris Eugenio, 後藤陽介, 水口佳一, 神原陽一, 脇田高徳, 村岡祐治, Saini Naurang L., 横谷尚睦

[Domestic presentation]  日本物理学会 第74回年次大会（2019年） (〒819-0395 福岡市西区元岡744 九州大学伊都キャンパス) , 

2019.03

, 

Oral presentation (general)

Magnetic and structural properties of superconducting mixed anion layered compound, La(Ca)FeAsO(F)

K. Kaneyasu, M. Matoba, Y. Kamihara

[International presentation]  The 5th Korea-Japan International Seminar on Materials Science and Engineering (KJMST2018), A Joint seminar with 2018 Fall conference of the Materials Research Society of Korea (Yeosu, Korea) , 

2018.11

, 

Poster presentation, K-MRS, MSSJ

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鉄系高温超伝導体のLa(Ca)FeAsO(F)はLaFeAsOを母相とした室温合成が可能な化学組成としては、最高の超伝導転移温度(Tc)　31.5 K を示す。 La(Ca)FeAsO(F)の磁性、格子定数の変化、及び局所構造変化を報告する。

Magnetic properties of perovskite-related mixed anion layered compounds, Sr2TMFeAsO3-delta, (TM: Cr, V)

KAMIHARA Yoichi

[International presentation]  The 5th Korea-Japan International Seminar on Materials Science and Engineering (KJMST2018), A Joint seminar with 2018 Fall conference of the Materials Research Society of Korea (Yeosu, Korea) , 

2018.11

, 

Oral presentation (invited, special), K-MRS, MSSJ

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ペロブスカイト型酸化物は強誘電体や強磁性体を含む機能性材料である。その電気的磁気的性質は1970年にGoodenoughとLongonによりまとめられた。このペロブスカイト関連層状酸化物をふくむ混合アニオン層状化合物Sr2TMFeAsO3-, (TM: Cr, V)の磁性を報告する。

Electrical structure and thermal properties of ZrCuSiAs type mixed anion layered compounds

M. Nakanishi, M. Matoba, Y. Kamihara

[International presentation]  The 5th Korea-Japan International Seminar on Materials Science and Engineering (KJMST2018), A Joint seminar with 2018 Fall conference of the Materials Research Society of Korea (Yeosu, Korea) , 

2018.11

, 

Poster presentation, K-MRS, MSSJ

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熱電変換材料の性能は無次元性能指数ZT=S2σT/κ、すなわちゼーベック係数(S)、電気伝導率(σ)、絶対温度(T)、熱伝導率(κ)より定義される。ZTが1を超えると実用的な熱電材料といえる。混合アニオン層状化合物の1111系BiCuSeOは1付近のZTを示すことが知られている。われわれは1111系AeMnPnF (Ae: アルカリ土類)の熱電変換性能を非経験的計算により部分的に予想した。