We report on the observations of ferromagnetic spin polarized moment and superconductivity in Sn nanoparticles. Ferromagnetic spin polarization, which is characterized by the appearance of Langevin magneticfield profiles for magnetization, persists even at room temperature. At temperatures below 15 K, magnetic hysteresis emerges in the weak applied magnetic-field regime. Enhanced superconductivity is found for particles with diameters smaller than 16 nm but larger than 9 nm. The presence of a magnetic field in the superconducting phase reveals a regime in which the magnetic susceptibility and magnetization increase with decreasing temperature. We attribute these behaviors to the coexistence of ferromagnetic spin polarized moment and superconductivity at low temperatures.
We report on the observations of spontaneous spin polarized moments in 7.4 nm Pb/PbO nanoparticles, which give rise to re-entrantlike temperature profiles for the magnetic susceptibility and magnetization in the superconducting phase that develops below 6.86 K. Results reveal the existence of a magnetic component below TC and superconductivity remains at low temperatures. A 30-fold increase in the critical magnetic field is also found. Superconductivity mainly arises from the 5 nm Pb core, whereas the 1.2 nm PbO shell contributes to the appearance of a net magnetic moment in the 7.4 nm Pb/PbO core/shell particles.
ARTICLEtransfer between the surface and core regions can result in a redistribution of conduction electrons that alters the available conduction electron density for Cooper pairing. Second, the internal magnetic field generated by the magnetic moments in the particle can also suppress the formations of Cooper pairs. Unfortunately, it is not feasible to draw a conclusion on the importance of each factor in the present study.
Magnetic susceptibility, x-ray diffraction, neutron diffraction and Raman scattering measurements are employed to study the effects of La substitution on the magnetic properties of multiferroic HoMn(2)O(5). 9% and 18% La-substituted compounds crystallize into the same orthorhombic Pbam symmetry as the parent compound. The magnetic responses to an ac driving magnetic field between 40 and 140 K are greatly enhanced by 18% La substitution. The neutron magnetic diffraction patterns reveal the development of short range magnetic correlations below 140 K. In addition, two Raman peaks and a series of new x-ray diffraction peaks suddenly develop below this temperature. Incommensurate long range antiferromagnetic order appears below 38 K. Magnetic frustration could be the main mechanism governing the present observations.
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