The High-Resolution Bitter Decoration Technique for the Magnetic Flux Structure Imaging at Low Temperatures

Abstract

The high-resolution Bitter technique for visualization (decoration) of the magnetic-flux structure in superconductors and magnets at low temperatures is presented. This method is based on the preparation of magnetic nanoparticles directly during a low-temperature experiment (in situ) by evaporating a magnetic material in the atmosphere of a buffer gas (helium) above the sample surface. An apparatus was constructed and a technique was proposed to stabilize the temperature of a sample during decoration with an accuracy of ±1 K within a wide temperature range. As an example, the results of observation of the magnetic-flux structure in single crystals of BSCCO(2212) high-temperature superconductor and EuFe₂(As_0.79P_0.21)₂ ferromagnetic superconductor at T ≤ 18 K are presented.