Advantages of λ measurement in flat geometry high-Tc cuprates by an open-flat coil magnetometer demonstrating its wide possibilities for detection

We developed an open-flat coil (OFC) preparation technology allowing creation of circular shape flat coils with high Q-factors. It enabled improving of an OFC magnetometer resolution up to Δλ∼0.5 Å (Δλ/λ∼3×10−7) at λ measurements in thin HTS at 30 MHz. This permitted to reach the sensitivity ∼2×10−12 W/cm2 at detection of 0.63 μm laser radiation, which is better than the possibilities of the similar “screening” type detector based however, on square shape flat coils. Besides, the resolution ∼30 nA/cm2 was registered at detection of the currents passing through the HTS thin films. We used this technique also to study the fine peculiarities of the vortex motion in high-Tc cuprates.