Surface resistance of YBa2Cu3O7 films on SrTiO3 and LaGaO3 substrates

Abstract

Surface resistance measurements of films of YBa2Cu3O7 deposited onto single-crystal substrates of LaGaO3 and SrTiO3 have been made at a frequency of 22 GHz. The measurements were made in either a copper or niobium cavity by replacing the end wall with the superconducting film. Typical surface resistance at 20 K are 1–2 mΩ for films on LaGaO3 and 6–8 mΩ for films on SrTiO3, as measured in the copper cavity. The LaGaO3 values lie within the sensitivity range of the Cu cavity (∼2 mΩ) and can only be considered upper limits. Similar measurements in a Nb superconducting cavity resulted in a surface resistance value of 0.2±0.1 mΩ at 4 K for the best LaGaO3-based film. This value is more than an order of magnitude lower than Cu, and suggests that LaGaO3-based films may offer immediate advantages in a number of applications.

High-pressure structural evolution of a perovskite solid solution (La1−x,Ndx)GaO3

“…For example, the (La, Nd)GaO 3 perovskites with Pbnm symmetry that were used in this study have become widely used substrate materials in the last decade because of their low lattice mismatch with high temperature superconductor (HTSC) films which is maintained even at high temperatures [1][2][3][4][5]. Tailoring elasticity and thermal expansion of such perovskites by adjusting the composition requires a detailed and systematic link to be developed between the crystal chemistry and their physical and thermodynamic properties.…”

Waveguides and Cavity Resonators

“…In this geometry no currents flow across the junction between the end wall and the body of the 50 -51 obtain the temperature dependence of the surface resistance R s of the end wall of a copper cavity by cooling to T = 15 K with a closed-cycle refrigerator and slowly warming to room temperature while measuring Q values. A computer-controlled network analyzer automatically determines the resonance peak and half-power points from which the cavity quality factor is calculated.…”

Surface resistance measurement of superconducting YBa2Cu3O7 in a magnetic field

“…SQUID susceptibility measurements show that from the Meissner effect the sample consists of -80% superconducting material. Though higher quality pellets have been fabricated and characterized by microwave measurements, 23 ' 24 the focus of this work is on the orientational averaging which is required for all but the oriented films and single crystal samples. 17 To determine the surface resistance of the superconductor, two disks were placed as end walls on a brass cylindrical cavity that is resonant at 16.5 GHz in the TE O n mode.…”