Hiroshi Kezuka

Growth Aspects of Thin-Film Composite Heterostructures of Oxide Multicomponent Perovskites for Electronics

We review, based on our results, the problems and solutions for the growth of thin films and composite heterostructures emphasizing the general growth aspects and principles vs specifics for each material or heterostructure. The materials used in our examples are Bi2Sr2Ca2Cu3O10, Bi2Sr2CaCu2O8, YBa2Cu3O7, (Sr, Ca)CuO2, (Ba, Ca)CuO2, and Bi4Ti3O12. The growth method was metal organic chemical vapor deposition (MOCVD). The presented thin films or heterostructures have c- and non-c-axis orientations. We discuss the implications of the film–substrate lattice relationships, paying attention to film–substrate lattice mismatch anisotropy and to film–film lattice mismatch, which has a significant influence on the quality of the non-c-axis heterostructures. We also present growth control through the use of vicinal substrates and two-temperature (template) and interrupted growth routes allowing significant quality improvements or optimization. Other key aspects of the growth mechanism, that is, roughness, morphology, and interdiffusion, are addressed. It is concluded that the requirements for the growth of non-c-axis heterostructures are more severe than those for the c-axis ones.

Hetero-epitaxial Growth of Cubic La(Sr)MnO3 on Hexagonal ZnO, In-Plane Orientations of La(Sr)MnO3 (001), (110), and (111) Phases

Hexagonal ZnO was grown on a hexagonal (001) sapphire substrate. Then cubic La(Sr)MnO3 (LSMO) was grown on a ZnO underlayer by ion beam sputtering at various substrate temperatures to obtain double-layers of LSMO/ZnO and to investigate hetero-epitaxial orientation growth. Out-of-plane (001)-oriented ZnO was grown with an in-plane orientation of [100](001)ZnO ∥ [110](001)sapphire (B-mode). Three phases of LSMO with out-of-plane (001), (110), and (111) orientations were grown on (001) ZnO generally. However, each single phase of LSMO could be grown only by controlling the deposition conditions. We achieved the in-plane orientation growth of LSMO, [110](001)LSMO ∥ [100](001)ZnO (B-mode), [10](110)LSMO ∥ [100](001)ZnO (A-mode), and [10](111)LSMO ∥ [110](001)ZnO (B-mode). The A-mode is defined as the mode in which both in-plane fundamental axes are parallel. The B-mode entails no parallel axes. The LSMO(001)- and (110)-grains have three equivalent in-plane domains, and the LSMO(111)-grain has a single domain. Lattice matching calculation can be used to partially interpret the orientation growth.

Growth Control of High-Tc Superconducting Thin Films for Future Electronics

1) Research Laboratory for Integrated Technological Systems, Kanazawa Institute of Technology, Hakusan, Ishikawa 924-0838, Japan Fax: +81-76-274-8273, e-mail: kendo@neptune.kanazawa-it.ac.jp 2) National Institute of Materials Physics, Bucharest-Magurele, POB MG-7, 077125, Romania 3) Advanced Materials Science R&D Center, Kanazawa Institute of Technology, Hakusan, Ishikawa 924-0838, Japan 4) School of Computer Science, Tokyo University of Technology, Hachioji, Tokyo 192-0982, Japan 5) National Institute for Materials Science, 1-2-1, Tsukuba, Ibaraki 305-0047, Japan 6) Graduate School of Engineering, Mie University, Tsu, Mie 514-8507, Japan

Magnetic characteristics of bulk BPSCCO magnetic sensors fabricated by the shock compaction method: relationship between the magnetic sensitivity and thickness of the magnetic sensor

As one of the basic areas of research for the development of a highly sensitive magnetic sensor, the present authors have fabricated bulk Bi-Pb-Sr-Ca-Cu-O magnetic sensors by use of the shock compaction method, as a new fabrication technique for high-critical temperature superconductors. Values of the thickness t of the sensors, under a shock compaction pressure P of 4 GPa, are systematically changed between 0.3 and 1.1 mm to investigate the magnetic sensitivity S of the sensors. It was found that the value of S increases as the value of t decreases. The value of S for a magnetic sensor (1.1 mm in width, 8.7 mm in length) was about 62 %/(104 T) over the range of measurement of the magnetic field Bmeas which varied from 0 to ±5×10-4 T, under a constant value of the bias magnetic field Bbias of 20×10-4 T. Namely, it was approximately 62 times greater than that of giant magnetoresistance sensor. In addition, the present paper examined the dependence of resistivity ρ(T) on temperature, the dependence of ρ(T=77.4 K) of the sensor on current density, the dependence of Son t, and the dependence of measured resistance of the magnetic field Rmeas on Bmeas.

Characteristics of a Bulk BPSCCO Magnetic Sensor Constructed by the Shock Compaction Method: Effect of the Shock Compaction Pressure on Magnetic Sensitivity

Recently, there has been an increased need for the development of a highly sensitive magnetic sensor for gathering new magnetic information. As one of the basic areas of research for the development of a highly sensitive magnetic sensor, the present authors have constructed a bulk Bi-Pb-Sr-Ca-Cu-O (BPSCCO) magnetic sensor by the shock compaction method as a new fabrication technique of the bulk high-critical temperature superconductor (HTS). Values of the shock compaction pressure are systematically changed between 1 and 9 GPa to investigate the magnetic sensitivity of the sensor. It was found that the value of was related to the value of . The magnetic sensitivity reached optimum values when maintaining a pressure of 1 GPa, being approximately , and about 11 times that of a giant magnetoresistance (GMR) sensor. The voltage fluctuation of a bulk BPSCCO sensor, when changing the value of , under a constant current density , was previously unknown. To help clarify this, systematic measurements were taken of the voltage noise power (VNP) spectrum of the sensor. The results lead to an important criterion for use in the design of a highly reliable and sensitive magnetic sensor.

Characterization of the surface of high-Tc YBaCuO

Abstract We investigated the characterization of mixed and annealed Y Ba Cu O superconductors with T c of around 90 K by scanning electron microscopy (SEM) with an energy dispersive X-ray system (EDS) for 99.99% (4N) and 99.995% (4N5) purity. EDS was perforned to investigate the composition on the surface of the specimens. Also, the chemical composition was analysed by inductively coupled plasma emission spectroscopy (ICP) for the 4N and 4N5 specimens. Y : Ba : Cu characterization results of EDS and ICP for 4N and 4N5 are as follows. For 4N: 14,418:35.173:50.409 at% (EDS); 17.3: 33.5: 49.1 at% (ICP). For 4N5: 15.468: 36.081: 48.452 at% (EDS); 16.6: 32.7: 50.5 at% (ICP).