Fabrication of All-Oxide Ferroelectric/High-Temperature Superconductor/Ferromagnetic Heterostructures for Electorically and Magnetically Tunable Microwava Devices

本报告主要是关于移动的通信用可调谐微波滤波器。为了实现大调谐和低插入损耗，我们提出了一种全氧化物超导体/铁电/铁磁异质结构的电磁可调谐超导微波滤波器，制备了YBa_2Cu_3O_7_y（YBCO），Ba_（0.05）Sr_（0.95）TiO_3（BSTO）和Pr_（0.85）Ca_（0.15）MnO_3（PCMO）单晶薄膜及YBCO/BSTO/PCMO异质结构半波长共面波导谐振腔。我们还研究了BSTO薄膜的电学性能和PCMP薄膜的磁电性能。此外，我们已经观察到的可调谐共面波导谐振器的谐振频率的变化与周围的7 GHz的谐振频率下的应用程序的电场和磁场。结果表明，通过施加电场，谐振频率的偏移约为7.5 MHz（可调谐性：约0.1%）。另一方面，通过施加磁场，偏移约为20 MHz（可调谐性;约0.25%）。这些值可用于可调应用。然而，这些值对于软件定义无线电的滤波器具有缺点。此外，由于其小的可调谐性，不能观察到在外加电场和磁场下的特性阻抗的保持效果。因此，我们提出了一个机械可调超导微波滤波器的基础上，这项研究技术。结果，我们获得了20%的大的可调性。

This report mainly concerns with tunable microwave filter for mobile telecommunications. In order to realize large tuning and lowinsertion loss, we propose an electrically and magnetically tunable superconducting microwave filters with all-oxide superconductor/ferroelectric/ferromagnetic heterostructures.We have fabricated YBa2Cu3O7y (YBCO), Ba0.05Sr0.95TiO3 (BSTO) and Pr0.85Ca0.15MnO3(PCMO) singlecrystal films and half-wavelength coplanar wave guide (CPW) resonator consisting of YBCO/BSTO/PCMO heterostructures. We have also investigated electric properties of the BSTO film and magnetic-electric properties of the PCMP film. Moreover, we have observed change of the resonant frequency of the tunable CPW resonator with the resonant frequency around 7 GHz under application of both electric and magnetic fields. The results show that the shift of the resonant frequency is about 7.5 MHz (tunability : about 0.1%) by an application of an electric field. On the other handk, the shift is about 20 MHz (tunability ; about 0.25%) by an application of a magnetic field. These values are available for use in the adjustable application. However, these values have a disadvantage for the filter of software-defined radio. Also, the keeping effect of the characteristic impedance under both applied electric and magnetic fields could not be observed because of its small tunability. Thus, we have proposed a mechanically tunable superconducting microwave filter based on this research technique. As a result, we have obtained the large tunability of 20%.