Study of fine peculiarities of heat capacity in $\mathrm{YBa_2Cu_3O_y}$ films by means of the laser-coupled flat-coil-oscillator

Improvements in the "hybrid” imaging method, based on traditional Laser Scanning Microscopy in combination with the single-layer flat-coil-oscillator (SFCO) sensitive technique introduced by authors earlier, are discussed. This method is capable of imaging $\mathrm{2D}$-grained structure, as well as the normal-tosuperconductive phase transition in flat thin high-$T_c$ superconductive materials with $1–2 \mu m$ spatial resolution. It enabled to detect weakly expressed peculiarities of the heat capacity in $\mathrm{YBa_2Cu_3O_y}$ film (preceding the well-known specific heat "jump”), which are important for true understanding of the real nature of superconductivity phenomenon. The method uses a well-focused $\mathrm{He-Ne}$ laser beam as a probing signal, and the SFCO-technique as a high-resolution sensing tool.