Weakly expressed “paramagnetic” peculiarity of the superconductive transition detected in YBaCuO film by highly sensitive OFC-magnetometer.

Single-layer open-flat coil-based tunnel diode oscillator (OFC-magnetometer) is sensitive to small changes of penetration depth of MHz-range magnetic field into plate-like high-<f>Tc</f> superconductivity (HTS) materials. <f>Δλ∼1</f>–3 A˚ absolute and better than <f>Δλ/λ∼10−6</f> relative resolution is reached, which corresponds to changes ∼1 pH of HTS film's magnetic inductance. It operates in high magnetic fields and measures the linear changes of <f>λ</f> in a wide dynamic range. Owing to pick-up coil's flat design, relatively low operation frequency and high relative resolution this method has advantages, compared to others, which become crucial at non-destructive studies with thin flat HTS materials (with a small signal), especially near <f>Tc</f> (at the start of “Cooper” pairs' formation). Due to these, a new “paramagnetic” (PM) peculiarity of superconductive transition was detected in YBaCuO film recently, which precedes well-known “diamagnetic” ejection. It specifies the details of an actually complicated shape of the N/S transition curve. In this report we discuss influence of the magnetic field on PM effect and relationship between the quality of HTS film and the amplitude of the effect. Differences between the PM effect and the known, externally similar, resistive “peak” as well as “paramagnetic Meissner” effects is shortly discussed too. [Copyright &y& Elsevier]