Samuele Sanna

Role of magnetic dopants in the phase diagram of Sm 1111 pnictides: The case of Mn

^{75}mathrm{As}

Effects of extremely low-frequency magnetotherapy on proliferation of human dermal fibroblasts

nuclear magnetic (NMR) and quadrupolar (NQR) resonance were used, together with Mossbauer spectroscopy, to investigate the magnetic state induced by Mn for Fe substitutions in F-doped

Persistence of slow dynamics in Tb(OETAP)(2) single molecule magnets embedded in conducting polymers.

{mathrm{LaFe}}_{1ensuremath{-}x}{mathrm{Mn}}_{x}mathrm{AsO}

Effect of external pressure on the magnetic properties of RCoAsO (R=La, Pr, Sm): a μSR study

superconductors. The results show that 0.5% of Mn doping is enough to suppress the superconducting transition temperature

Investigation of Li and H dynamics in Li6C60 and Li6C60Hy

{T}_{c}

Extending the hydrogen storage limit in fullerene

from 27 K to zero and to recover the magnetic structure observed in the parent undoped LaFeAsO. Also the tetragonal to orthorhombic transition of the parent compound is recovered by introducing Mn, as evidenced by a sharp drop of the NQR frequency. The NQR spectra also show that a charge localization process is at play in the system. Theoretical calculations using a realistic five-band model show that correlation-enhanced RKKY exchange interactions between nearby Mn ions stabilize the observed stripe magnetic order. These results give compelling evidence that F-doped LaFeAsO is a strongly correlated electron system at the verge of an electronic instability.

Molecular and Ionic Dynamics in NaxLi6–xC60

The deliberate insertion of magnetic Mn dopants in the Fe sites of the optimally-doped SmFeAsO0.88-F0.12 iron-based superconductor can modify in a controlled way its electronic properties. The resulting phase diagram was investigated across a wide range of manganese contents (x) by means of muon-spin spectroscopy (muSR), both in zero- and in transverse fields, respectively, to probe the magnetic and the superconducting order. The pure superconducting phase (at x < 0.03) is replaced by a crossover region at intermediate Mn values (0.03 =< x < 0.08), where superconductivity coexists with static magnetic order. After completely suppressing superconductivity for x = 0.08, a further increase in Mn content reinforces the natural tendency towards antiferromagnetic correlations among the magnetic Mn ions. The sharp drop of Tc and the induced magnetic order in the presence of magnetic disorder/dopants, such as Mn, are both consistent with a recent theoretical model of unconventional superconductors [M. Gastiasoro et al., ArXiv 1606.09495], which includes correlation-enhanced RKKY-couplings between the impurity moments.

Evidence of local structural order and spin-lattice coupling in the frustrated pyrochloreY2Ru2O7

ABSTRACT Extremely low-frequency electromagnetic fields (ELF-EMFs) applied in magnetotherapy have frequency lower than 100 Hz and magnetic field intensity ranging from 0.1 to 20 mT. For many years, the use of magnetotherapy in clinics has been increasing because of its beneficial effects in many processes, e.g., skin diseases, inflammation and bone disorders. However, the understanding of the microscopic mechanisms governing such processes is still lacking and the results of the studies on the effects of ELF-EMFs are controversial because effects derive from different conditions and from intrinsic responsiveness of different cell types.In the present study, we studied the biological effects of 1.5 h exposure of human dermal fibroblasts to EMFs with frequencies of 5 and 50 Hz and intensity between 0.25 and 1.6 mT. Our data showed that the magnetic treatment did not produce changes in cell viability, but gave evidence of a sizeable decrease in proliferation at 24 h after treatment. In addition, immunofluorescence experiments displayed an increase in tubulin expression that could foreshadow changes in cell motility or morphology. The decrease in proliferation with unchanged viability and increase in tubulin expression could be consistent with the triggering of a transdifferentiation process after the exposure to ELF-EMFs.

H and Li dynamics in Li12C60 and Li12C60Hy

UNLABELLEDnThe spin dynamics of Tb(OETAP)2 single ion magnets was investigated by means of muon spin relaxation (μSR) both in the bulk material as well as when the molecule is embedded intonnnPEDOTnPSS polymer conductor. The spin fluctuation time is characterized by a high temperature activated trend, with an energy barrier around 320 K, and by a low temperature tunneling regime. When the single ion magnet is embedded into the polymer the energy barrier only slightly decreases and the fluctuation time remains of the same order of magnitude, even at low temperature. This finding shows that these single molecule magnets preserve their characteristics which, if combined with those of the conducting polymer, result in a hybrid material of potential interest for organic spintronics.