Magnetic molecules as sensors of topological hysteresis of superconductors

Superconductors and magnetic materials, including molecules, are key ingredients for quantum and advanced spintronic applications. However, only a little is known about how these materials are mutually influenced at their interface in hybrid architectures. Here, we show that a single layer of magnetic molecules, the Terbium(III) bis-phthalocyaninato (TbPc2) complexes, deposited on a superconducting Pb(111) surface is sensitive to the topology of the intermediate state of the superconductor, namely to the presence and evolution of superconducting and normal domains due to the magnetic field screening and penetration. The evidence of this sensitivity is found in the magnetisation dynamics of the TbPc2 sub-monolayer in its paramagnetic regime showing the fingerprint of the topological hysteresis of the superconducting substrate. This study reveals the great potentialities hold by thin layers of magnetic molecules for sensing local magnetic field variation in hybrid molecular/superconductor architectures, including spin resonators or spin injection devices for spintronics applications.

Leakage magnetic field variation induced by inner surface grooves during loading in geomagnetic environment

The leakage magnetic field which induced by the inner surface groove during loading had been measured from the outer surface in geomagnetic environment. Compared the variation of the leakage magnetic field along the load with the location and development of the groove, it was found that two phenomena are relate to the magnetic field aberration. The relation can be described by the pink-pink value and the gradient of the magnetic field aberration. This result can be used to evaluate and monitor the inner defect by the magnetic field aberration characters.

Double plasma-resonance surfaces in flare loops and radio zebra emission

Aims. The zebra structures observed in radio waves during solar flares are some of the most important structures used as diagnostics of solar flare plasmas. We here not only analyze the so-called double plasma-resonance (DPR) surfaces, but also estimate the effects of their form on the size of the zebra sources and brightness temperature. Methods. To compute the DPR surfaces, we used numerical and analytical methods. Results. We found that except for the case of a constant magnetic field across the loop, the DPR surfaces deviate from the constant plasma density surfaces. We found that the regime with a finite height scale has three forms of resonance surfaces depending on the magnetic field variation across the loop. This magnetic field variation also determines if in the generated zebra structure, an increase in gyro-harmonic number leads to an increase or decrease of the zebra stripe frequency. In the case with an infinite height scale, the resonance surfaces are parallel to the loop axis. Furthermore, we found that for highly polarized zebra structures that are generated at DPR surfaces close to the plasma frequency, the zebra emission is limited to the narrow escaping cone and the emitting source area increases with increasing viewing angle compared to the loop axis. Moreover, with increasing deviation of the DPR surfaces from those of constant density surfaces, the frequency bandwidth of the DPR emission increases and can cause the zebra stripes to overlap, which limits the zebra generation. For the zebra structures observed on 14 February 1999, 6 June 2000, and 1 August 2010 and the observed view perpendicular to the loop axis, we estimated that the brightness temperature is 3.67 × 1014 K, 6.58 × 1013 K, and 7.35 × 1015 K, respectively. These brightness temperatures are much lower than those derived for the view along the loop axis (up to 1017 K), and thus are more realistic. The area of the emitting source for coronal loops in the view perpendicular to the loop axis can be larger by several orders of magnitude than that in the view along the loop axis.