P. Bonfà

s-wave pairing in the optimally doped LaO_{0.5}F_{0.5}BiS_{2} superconductor

We report on the magnetic and superconducting properties of LaO0.5F0.5BiS2 by means of zero- (ZF) and transverse-field (TF) muon-spin spectroscopy measurements (uSR). Contrary to previous results on iron-based superconductors, measurements in zero field demonstrate the absence of magnetically ordered phases. TF-uSR data give access to the superfluid density, which shows a marked 2D character with a dominant s-wave temperature behavior. The field dependence of the magnetic penetration depth confirms this finding and further suggests the presence of an anisotropic superconducting gap.

Correlated trends of coexisting magnetism and superconductivity in optimally electron-doped oxypnictides.

We report on the recovery of the short-range static magnetic order and on the concomitant degradation of the superconducting state in optimally F-doped SmFe(1-x)Ru(x)AsO(0.85)F(0.15) for 0.1≤x≲0.5. The two reduced order parameters coexist within nanometer-size domains in the FeAs layers and eventually disappear around a common critical threshold x(c)~0.6. Superconductivity and magnetism are shown to be closely related to two distinct well-defined local electronic environments of the FeAs layers. The two transition temperatures, controlled by the isoelectronic and diamagnetic Ru substitution, scale with the volume fraction of the corresponding environments. This fact indicates that superconductivity is assisted by magnetic fluctuations, which are frozen whenever a short-range static order appears, and totally vanish above the magnetic dilution threshold x(c).

Effect of external pressure on the magnetic properties of LnFeAsO (Ln = La, Ce, Pr, Sm)

We investigate the effect of external pressure on magnetic order in undoped LnFeAsO (Ln =La, Ce, Pr, Sm) by using muon spin relaxation measurements and ab initio calculations. Both the magnetic transition temperature Tm and the Fe magnetic moment decrease with external pressure. The effect is observed to be lanthanide dependent, with the strongest response for Ln = La and the weakest for Ln = Sm. The trend is qualitatively in agreement with our density functional theory calculations. The same calculations allow us to assign a value of 0.68(2) μB to the Fe moment, obtained from an accurate determination of the muon sites. Our data further show that the magnetic lanthanide order transitions do not follow the simple trend of Fe, possibly as a consequence of the different f-electron overlap.

Poisoning effect of Mn in LaFe1-xMnxAsO0.89F0.11: Unveiling a quantum critical point in the phase diagram of iron-based superconductors

A superconducting-to-magnetic transition is reported for LaFe

Ab initio strategy for muon site assignment in wide band gap fluorides

_{1-x}

Common effect of chemical and external pressures on the magnetic properties of RCoPO (R = La, Pr, Nd, Sm). II.

Mn

Toward the Computational Prediction of Muon Sites and Interaction Parameters

_x

Slow magnetic fluctuations and superconductivity in fluorine-doped NdFeAsO

AsO

Magnetic states of MnP: muon-spin rotation studies

_{0.89}

Magnetic ground state and spin fluctuations in MnGe chiral magnet as studied by muon spin rotation

F