The improved 'LC-resonator' technique (the open-flat coil magnetometer), based on a low-power stable-frequency tunnel diode oscillator with a single-layer open-faced coil, is very sensitive to changes of position. About 1 Å absolute and better than 10-6 relative resolution can be reached in distance change measurements. It is an excellent MHz-range scientific instrument with which one may study weakly expressed fine peculiarities of the superconductive state in small-volume thin plate-like high-Tc superconductors (HTS). It enables changes to be detected of about 1 pH of the HTS film's magnetic inductance (changes of ∼1-3 Å of the magnetic penetration depth, λ) with very high (∼10-6) relative resolution. Owing to the pick-up coil's flat design, relatively low operation frequency and high relative resolution, the present method has advantages over others. It is essential for non-destructive studies of thin flat HTS materials (with a small signal) especially near Tc (at the beginning of the formation of 'Cooper' pairs). Mainly as the result of these advantages a new 'paramagnetic' peculiarity of the superconductive transition has been detected in Y-Ba-Cu-O film, which precedes the well known 'diamagnetic' ejection. A possible explanation of the observed effect is given, and the influence of some external physical parameters on the effect is revealed and discussed.
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Condensed Matter Physics
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry