Study on Electrical Conductivity and Hall Effect Spectra in a Non-Cuprate High-Tc Superconductive Oxide

非铜氧化物高温超导氧化物的电导率和霍尔效应谱研究

• 批准号: 07640463
• 负责人: MINAMI Hidetoshi
• 金额: $ 1.47万
• 依托单位: University of Tsukuba
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640463/
• 关键词: Superconductive Oxide; Non-cuprate; Ba_1-xKxBiO_3; Electrochemical Synthesis; Electrical Conductivity; Hall Effect; Photoconductivity; Electronic State; 電気化学合成法; 光伝導の磁気効果

The present study was performed with the aim of investigating the mechanisms of semiconductor-superconductor transition and electrical conductivity, electronic state and electronic structure in a non-cuprate superconductive oxide Ba_1-xKxBiO_3 with high-Tc (Tc_<max>=32K) in the superconducting phase. The study includes (1) synthesis and characterization of single crystals and (2) studies of electrical conductivity, Hall effect, optical spectroscopy, magnetic property and photoconductivity and the magnetic field effect.1.Single crystals of Ba_1-xKxBiO_3 with little potassium deficiency in wide composition range covering from semiconductive to superconducting phases were synthesized by an electrochemical method with a composition (x) control technique by changing the amount of water vapor in atmosphere covering melt. We extended our studies to the successful fabrication of tunnel structure all composed of Ba_1-xKxBiO_3 by adopting this x control technique during the crystal growth.2.From … More the detailed analysis of the Hall effect in superconductive Ba_1-xKxBiO_3 (x=0.42), we clarified the importance of optical phonon scattering of electrons in the mechanism of conductivity. Temperature dependence of the Hall effect has been for the first time studied in the semiconductive phase (x<0.3). Activation type behavior of positive hole density was observed for 0*x*0.19. It was found that mass of positive hole is extremely heavy. For x=0.19, the contribution of electrons to conductivity is clearly observed above 200K.Photoconductive signal has been observed for the first time in semiconductive Ba_1-xKxBiO_3. In order to investigate the phenomenon in details, further research is on progress. By analyzing effective charges of ions from the previously reported experimental results of phonon spectrum and XPS,a much more covalent character of BaBiO_3 than expected by the band calculation has been observed. Thus, we reconfirmed that semiconductive nature of BaBiO_3 and semiconductive phase of related superconductors should be explained without the scenario of split-off by 3D-CDW formation of the wide band composed of Bi (6s) -O (2p). Less

本文研究了高Tc（Tc = 32 K）非铜氧化物Ba_1-xKxBiO_3超导相的超导-超导转变机制、电导率、电子态和电子结构<max>。研究内容包括：（1）单晶的合成和表征;（2）电导率、霍尔效应、光谱学、1.用电化学方法合成了Ba_1-xKxBiO_3单晶，其组成为（x）：通过改变大气中覆盖熔体的水蒸气量来控制技术。在晶体生长过程中采用这种x控制技术，成功地制备了Ba_1-xKxBiO_3隧道结构 ...更多信息 通过对Ba_1-xK_xBiO_3（x=0.42）中霍尔效应的详细分析，阐明了电子的光学声子散射在导电机理中的重要性。首次研究了在α相（x&lt;0.3）中霍尔效应的温度依赖性。对于0*x*0.19，观察到正空穴密度的活化型行为。发现正空穴的质量非常大。当x=0.19时，在200 K以上观察到电子对电导率的贡献，并首次在Ba_1-xKxBiO_3中观察到光电导信号。为了更详细地研究这一现象，进一步的研究正在进行中。从声子谱和XPS的实验结果分析离子的有效电荷，发现BaBiO_3具有比能带计算所预期的更强的共价性。因此，我们重新确认了BaBiO_3的超导性质和相关超导体的超导相的性质，不需要用Bi（6s）-O（2 p）组成的宽带的3D-CDW分裂来解释。少

项目成果

H.Minami: "SIS Structure of Ba_1-xKxBiO_3 Fabricated by an Electrochemical Method" Advances in Superconductivity. IX. (1997)

H.Minami：“电化学方法制造的 Ba_1-xKxBiO_3 的 SIS 结构”超导进展。

H.Uwe, Xiaoli Ji and H.Minami: "Magnetic Susceptibility of Single Crystalline Ba_1-xKxBiO_<3-y>" Czechoslovak J.Phys.Suppl.S5 46. 2691-2692 (1996)

H.Uwe、季晓丽和 H.Minami：“单晶 Ba_1-xKxBiO_<3-y> 的磁化率”捷克斯洛伐克 J.Phys.Suppl.S5 46. 2691-2692 (1996)

H.Minami and H.Uwe: "SIS Structure of Ba_1-xKxBiO_3 Fabricated by an Electrochemical Method" Advances in Superconductivity IX (Proc.9th Int.Sym.Superconductivity). (in print.). (1997)

H.Minami 和 H.Uwe：“电化学方法制备的 Ba_1-xKxBiO_3 的 SIS 结构”超导进展 IX（Proc.9th Int.Sym.Superconductivity）。

H.T.Kim, H.Minami, W.Schmidtbauer, J.W.Hodby, A.Iyo, F.Iga and H.Uwe: "Paramagnetic Meissner Effect in Superconducting Single Crystals of Ba_1-xKxBiO_3" J.Low Temperature Physics. 105. 557-562 (1996)

H.T.Kim、H.Minami、W.Schmidtbauer、J.W.Hodby、A.Iyo、F.Iga 和 H.Uwe：“Ba_1-xKxBiO_3 超导单晶中的顺磁迈斯纳效应”J.低温物理学。

H.Minami and H.Uwe: "Mobility of Positive Holes in YBa_2Cu_3O_<7-y> -Effects of Oxygen Deficiency and Light Irradiation" Physica C (Proc. M^2S-HTSC V). (in print.). (1997)

H.Minami 和 H.Uwe：“YBa_2Cu_3O_<7-y> 中正空穴的迁移率 - 缺氧和光照射的影响”Physica C（Proc. M^2S-HTSC V）。